Month: November 2024

Jharkhand Board JAC Class 10 Maths Solutions Chapter 4 Quadratic Equations Ex 4.3 Textbook Exercise Questions and Answers.

JAC Board Class 10 Maths Solutions Chapter 4 Quadratic Equations Exercise 4.3

Question 1.
Find the roots of the following quadratic equations, if they exist, by the method of completing the square:
1. 2x² – 7x + 3 = 0
2. 2x² + x – 4 = 0
3. 4x² + 4\(\sqrt{3}\)x + 3 = 0
4. 2x² + x + 4 = 0
Solution:
1. 2x² – 7x + 3 = 0
Dividing throughout by 2, we get

Thus, the roots of the given quadratic equation are 3 and \(\frac{1}{2}\).

2. 2x² + x – 4 = 0
Dividing throughout by 2, we get

Thus, the roots of the given quadratic equation are \(\frac{-1+\sqrt{33}}{4}\) and \(\frac{-1-\sqrt{33}}{4}\)

3. 4x² + 4\(\sqrt{2}\)x + 3 = 0
4x² + 4\(\sqrt{3}\)x + (\(\sqrt{3}\))² = 0
(2x + \(\sqrt{3}\))² = 0
(2x + \(\sqrt{3}\)) (2x + \(\sqrt{3}\)) = 0
2x + \(\sqrt{3}\) = 0 or 2x + \(\sqrt{3}\) =0
x = \(-\frac{\sqrt{3}}{2}\) or x = \(-\frac{\sqrt{3}}{2}\)
Thus, the roots of the given quadratic equation are \(-\frac{\sqrt{3}}{2}\) and \(-\frac{\sqrt{3}}{2}\)

4. 2x² + x + 4 = 0
Dividing throughout by 2, we get

But, the square of any real number cannot be negative.
Hence, the real roots of the given quadratic equation do not exist.

Question 2.
Find the roots of the quadratic equations given in Q.1 by applying the quadratic formula.
1. 2x² – 7x + 3 = 0
Here, a = 2, b = -7 and c = 3.
Then, b² – 4ac = (-7)² – 4(2)(3) = 25
Now, x = \(\frac{-b \pm \sqrt{b^2-4 a c}}{2 a}\)
∴ x = \(\frac{7 \pm \sqrt{25}}{2(2)}\)
∴ x = \(\frac{7 \pm 5}{4}\)
∴ x = 3 or x = \(\frac{1}{2}\)
Thus, the roots of the given quadratic equation are 3 and \(\frac{1}{2}\).

2. 2x² + x – 4 = 0
Here, a = 2, b = 1 and c = -4.
Then, b² – 4ac = (1)² – 4(2)(-4) = 33
Now, x = \(\frac{-b \pm \sqrt{b^2-4 a c}}{2 a}\)
∴ x = \(\frac{-1 \pm \sqrt{33}}{2(2)}\)
∴ x = \(\frac{-1 \pm \sqrt{33}}{4}\)
Thus, the roots of the given quadratic equation are \(\frac{-1 \pm \sqrt{33}}{4}\) and \(\frac{-1-\sqrt{33}}{4}\)

3. 4x² + 4\(\sqrt{3}\)x + 3 = 0
Here, a = 4, b = 4\(\sqrt{3}\) and c = 3.
Then, b² – 4ac = (4\(\sqrt{3}\))² – 4(4)(3) = 0
Then, x = \(\frac{-b \pm \sqrt{b^2-4 a c}}{2 a}\)
∴ x = \(\frac{-4 \sqrt{3} \pm \sqrt{0}}{2(4)}\)
∴ x = \(-\frac{\sqrt{3}}{2}\) or x = \(-\frac{\sqrt{3}}{2}\)
Thus, the roots of the given quadratic equation are \(-\frac{\sqrt{3}}{2}\) and \(-\frac{\sqrt{3}}{2}\).

4. 2x² + x + 4 = 0
Here, a = 2, b = 1 and c = 4.
Then, b² – 4ac = (1)² – 4 (2)(4) = -31 < 0
Since b² – 4ac < 0 for the given quadratic equation, the real roots of the given quadratic equation do not exits.

Question 3.
Find the roots of the following equations:
1. x – \(\frac{1}{x}\) = 3, x ≠ 0
2. \(\frac{1}{x+4}-\frac{1}{x-7}=\frac{11}{30}\); x ≠ -4, 7
Solution:
1. x – \(\frac{1}{x}\) = 3, x ≠ 0
∴ x² – 1 = 3x
∴ x² – 3x – 1 = 0
Here, a = 1, b = -3 and c = -1.
Then, b² – 4ac = (-3)² – 4(1)(-1) = 13
Now, x = \(\frac{-b \pm \sqrt{b^2-4 a c}}{2 a}\)
x = \(\frac{3 \pm \sqrt{13}}{2(1)}\)
x = \(\frac{3 \pm \sqrt{13}}{2}\)
Thus, the roots of the given equation are \(\frac{3+\sqrt{13}}{2}\) and \(\frac{3-\sqrt{13}}{2}\).

2. \(\frac{1}{x+4}-\frac{1}{x-7}=\frac{11}{30}\); x ≠ -4, 7
∴ \(\frac{(x-7)-(x+4)}{(x+4)(x-7)}=\frac{11}{30}\)
∴ \(\frac{-11}{x^2-3 x-28}=\frac{11}{30}\)
∴ \(\frac{-1}{x^2-3 x-28}=\frac{1}{30}\)
∴ -30 = x² – 3x – 28
∴ x² – 3x + 2 = 0
Here, a = 1, b = -3 and c = 2.
Then, b² – 4ac = (-3)² – 4(1)(2) = 1
Now, x = \(\frac{-b \pm \sqrt{b^2-4 a c}}{2 a}\)
∴ x = \(\frac{3 \pm \sqrt{1}}{2(1)}\)
∴ x = \(\frac{3 \pm 1}{2}\)
∴ x = 2 or x = 1
Thus, the roots of the given equation are 2 and 1.
Note: Here, the method of factorisation would turn out to be more easier.

Question 4.
The sum of the reciprocals of Rehman’s ages (in years), 3 years ago and 5 years from now is \(\frac{1}{3}\). Find his present age.
Solution:
Let the present age of Rehman be x years.
So, his age 3 years ago was (x – 3) years and his age 5 years hence will be (x + 5) years.
The sum of the reciprocals of these two ages (in years) is given to be \(\frac{1}{3}\).
∴ \(\frac{1}{x-3}+\frac{1}{x+5}=\frac{1}{3}\)
∴ \(\frac{x+5+x-3}{(x-3)(x+5)}=\frac{1}{3}\)
∴ 3(2x + 2) = (x – 3)(x + 5)
∴ 6x + 6 = x² + 2x – 15
∴ x² – 4x – 21 = 0
∴ x² – 7x + 3x – 21 = 0
∴ x(x – 7) + 3(x – 7) = 0
∴ (x – 7)(x + 3) = 0
∴ x – 7 = 0 or x + 3 = 0
∴ x = 7 or x = -3
Now, since x represents the present age of Rehman, it cannot be negative, i,e., x ≠ -3.
∴ x = 7
Thus, the present age of Rehman is 7 years.

Question 5.
In a class test, the sum of Shefali’s marks in Mathematics and English is 30. Had she got 2 marks more in Mathematics and 3 marks less in English, the product of those marks would have been 210. Find her marks in the two subjects.
Solution:
Let Shefali’s marks in Mathematics be x.
Then, her marks in English = 30 – x, as her total marks in Mathematics and English is 30.
Had she scored 2 marks more in Mathematics and 3 marks less in English, her score in Mathematics would be x + 2 and in English would be 30 – x – 3 = 27 – x.
∴ (x + 2) (27 – x) = 210
∴ 27x – x² + 54 – 2x = 210
∴ -x² + 25x + 54 – 210 = 0
∴ -x² + 25x – 156 = 0
∴ x² – 25x + 156 = 0
∴ x² – 13x – 12x + 156 = 0
∴ x(x – 13) – 12(x – 13) = 0
∴ (x – 13)(x – 12) = 0
∴ x – 13 = 0 or x – 12 = 0
∴ x = 13 or x = 12
Then, 30 – x = 30 – 13 = 17 or
30 – x = 30 – 12 = 18
Thus, Shefall’s marks in Mathematics and in English are 13 and 17 respectively or 12 and 18 respectively.

Question 6.
The diagonal of a rectangular field is 60 metres more than the shorter side. If the longer side is 30 metres more than the shorter side, find the sides of the field.
Solution:
Let the shorter side of the rectangular field be x m.
Then, it diagonal is (x + 60) m and the longer side is (x + 30) m.
In a rectangle, all the angles are right angles.
Hence, by Pythagoras theorem,
(Shorter side)² + (Longer side)² = (Diagonal)²
∴ x² + (x + 30)² = (x + 60)²
∴ x² + x² + 60x + 900 = x² + 120x + 3600
∴ x² – 60x – 2700 = 0
Here, a = 1, b = -60 and c = -2700.
Then, b² – 4ac = (-60)² – 4(1)(-2700)
= 3600 + 10800
= 14400
Now, x = \(\frac{-b \pm \sqrt{b^2-4 a c}}{2 a}\)
= \(\frac{60 \pm \sqrt{14400}}{2(1)}\)
= \(\frac{60 \pm 120}{2}\)
∴ x = \(\frac{60+120}{2}\) or x = \(\frac{60-120}{2}\)
∴ x = 90 or x = -30
Since x denotes the shorter side of the rectangular field, x cannot be negative.
∴ x = 90
Then, x + 30 = 90 + 30 = 120
Thus, the shorter side (breadth) of the rectangular field is 90 m and the longer side (length) of the rectangular field is 120 m.

Question 7.
The difference of squares of two numbers is 180. The square of the smaller number is 8 times the larger number. Find the two numbers.
Solution:
Let the smaller number be x.
Then, the larger number = \(\frac{x^2}{8}\)
Now, the difference of their squares is 180.
∴ \(\left(\frac{x^2}{8}\right)^2-(x)^2=180\)
∴ \(\frac{x^4}{64}-x^2=180\)
∴ x⁴ – 64x² – 11520 = 0
Let x² = y
∴ x⁴ = y²
∴ y² – 64y – 11520 = 0
Here, a = 1, b = -64 and c = -11520.
Then, b² – 4ac = (-64)² – 4(1)(-11520)
= 4096 + 46080
= 50176
Now, y = \(\frac{-b \pm \sqrt{b^2-4 a c}}{2 a}\)
= \(\frac{64 \pm \sqrt{50176}}{2(1)}\)
= \(\frac{64 \pm 224}{2}\)
∴ y = \(\frac{64+224}{2}\) or y = \(\frac{64-224}{2}\)
∴ y = 144 or y = -80
∴ x² = 144 or x² = -80
But, x² = -80 is not possible.
∴ x² = 144
∴ x = 12 or x = -12
Then, \(\frac{x^2}{8}=\frac{144}{8}=18\)
Thus, the required numbers are 12 and 18 or -12 and 18.

Question 8.
A train travels 360 km at a uniform speed. If the speed had been 5 km/h more, it would have taken 1 hour less for the same journey. Find the speed of the train.
Solution:
Let the usual uniform speed of the train be x km/h.
∴ Time taken to travel 360 km at the speed of x km/h = \(\frac{\text { distance }}{\text { speed }}\) = \(\frac{360}{x}\) hours.
If the speed had been 5 km/h more, the new speed would be (x + 5) km/h and the time taken to travel 360 km at this increased speed would be \(\frac{360}{x+5}\) hours.
Now, New time = Usual time – 1
∴ \(\frac{360}{x+5}=\frac{360}{x}-1\)
∴ 360x = 360x + 1800 – x(x + 5) (Multiplying by x(x + 5))
∴ 0 = 1800 – x² – 5x
∴ x² + 5x – 1800 = 0
∴ x² + 45x – 40x – 1800 = 0
∴ x(x + 45) – 40(x + 45) = 0
∴ (x + 45) (x – 40) = 0
∴ x + 45 = 0 or x – 40 = 0
∴ x = -45 or x = 40
As, x is the speed (in km/h) of the train, x = -45 is not possible.
∴ x = 40
Thus, the usual uniform speed of the train is 40 km/h.

Question 9.
Two water taps together can fill a tank in \(9 \frac{3}{8}\) hours. The tap of larger diameter takes 10 hours less than the smaller one to fill the tank separately. Find the time in which each tap can separately fill the tank.
Solution:
Let the time taken by the tap with smaller diameter to fill the tank be x hours.
Then, the time taken by the tap with larger diameter = (x – 10) hours.
So, the part of the tank filled in one hour by the tap with smaller diameter = \(\frac{1}{x}\) and by the tap with larger diameter = \(\left(\frac{1}{x-10}\right)\)
So, the part of tank filled in one hour by both the taps together = \(\frac{1}{x}+\frac{1}{x-10}\)
Both the taps together can fill the tank in \(9 \frac{3}{8}\) hours, i.e., \(\frac{75}{8}\) hours.
∴ The part of tank filled in one hour by both the tank together = \(\frac{8}{75}\)
∴ \(\frac{1}{x}+\frac{1}{x-10}=\frac{8}{75}\).
∴ 75(x – 10) + 75x = 8x (x – 10) (Multiplying by 75x(x – 10))
∴ 75x – 750 + 75x = 8x² – 80x
∴ 8x² – 230x + 750 = 0
Here, a = 8, b = -230 and c = 750.
∴ b² – 4ac = (-230)² – 4 (8)(750)
= 52900 – 24000
= 28900
Now, x = \(\frac{-b \pm \sqrt{b^2-4 a c}}{2 a}\)
∴ x = \(\frac{230 \pm \sqrt{28900}}{2(8)}\)
∴ x = \(\frac{230 \pm 170}{16}\)
∴ x = \(\frac{400}{16}\) or x = \(\frac{60}{16}\)
∴ x = 25 or x = 3.75
But, x ≠ 3.75, because for x = 3.75, x – 10 < 0.
∴ x = 25 and x – 10 = 15
Thus, the time taken by the tap with smaller diameter is 25 hours and that by the tap. with larger diameter is 15 hours.

Question 10.
An express train takes 1 hour less than a passenger train to travel 132 km between Mysore and Bangalore (without taking into consideration the time they stop at intermediate stations). If the average speed of the express train is 11 km/h more than that of the passenger train, find the average speed of the two trains.
Solution:
Let the average speed of the passenger train be x km/h.
Then, the average speed of the express train is (x + 11) km/h.
∴ Time taken by passenger train to cover 132 km = \(\frac{132}{x}\) hours.
∴ Time taken by express train to cover 132 km = \(\frac{132}{x+11}\) hours.
Time taken by express train = Time taken by passenger train – 1
\(\frac{132}{x+11}=\frac{132}{x}-1\)
∴ 132x = 132(x + 11) – x(x + 11) (Multiplying by x(x + 11))
∴ 132x = 132x + 1452 – x² – 11x
∴ x² + 11x – 1452 = 0
Here, a = 1, b = 11 and c = -1452.
∴ b² – 4ac = (11)² – 4(1)(-1452)
= 121 + 5808 = 5929
Now, x = \(\frac{-b \pm \sqrt{b^2-4 a c}}{2 a}\)
∴ x = \(\frac{-11 \pm \sqrt{5929}}{2(1)}\)
∴ x = \(\frac{-11 \pm 77}{2}\)
x = 33 or x = -44
x = -44 is inadmissible as x represents the speed of the passenger train.
∴ x = 33 and x + 11 = 44
Thus, the speed of the passenger train is 33 km/h and the speed of the express train is 44 km/h.

Question 11.
Sum of the areas of two squares is 468 m². If the difference of their perimeters is 24 m, find the sides of the two squares.
Solution:
Let the side of the smaller square be x m.
Then, the perimeter of the smaller square = 4x m
and the area of the smaller square = x² m².
From the given, the perimeter of the bigger square = (4x + 24) m.
∴ Side of the bigger square = \(\frac{4 x+24}{4}\) = (x + 6) m and hence, the area of the bigger square = (x + 6)² m².
∴ x² + (x + 6)² = 468
∴ x² + x² + 12x + 36 – 468 = 0
∴ 2x² + 12x – 432 = 0
∴ x² + 6x – 216 = 0
∴ x² + 18x – 12x – 216 = 0
∴ x(x + 18) – 12(x + 18) = 0
∴ (x + 18) (x – 12) = 0
∴ x + 18 = 0 or x – 12 = 0
∴ x = -18 or x = 12
Here, x = -18 is not possible as x represents the side of a square.
∴ x = 12 and x + 6 = 18
Thus, the side of the smaller square is 12 m and the side of the bigger square is 18 m.

JAC Board Class 9th Social Science Notes History Chapter 4 Forest Society and Colonialism Notes

→ Introduction

• Forests provide us various natural resources of economic and medicinal value.
• Due to increasing population and rapid industrialisation, world’s forest areas are disappearing at fast rate.
• The disappearance of forests is referred to as deforestation.

→  Why Deforestation?

• The process of deforestation began many centuries ago in India. Under colonial rule, it became more systematic and extensive.
• As population increased over the centuries and the demand for food went up, peasants extended the boundaries of cultivation, clearing forests and breaking new land.

→ Land to be Improved

• Forests disappeared to a great extent and cultivation area rose by 6.7 million hectares between 1880 and 1920.
• Sleepers on the Tracks
• The spread of railways from the 1850s created a new demand. To run locomotives, wood was needed as fuel, and to lay railway lines, sleepers were essential to hold the tracks together.
• As the railway tracks spread through India, a larger and larger number of trees were felled.

→ Plantations

• Large areas of natural forests were also cleared to make way for tea, coffee and rubber plantations to meet Europe’s growing need for these commodities.

→ The Rise of Commercial Forestry

• The British were worried that the use of forests by local people and the reckless felling of trees by traders would destroy the forests. So they decided to invite a German expert, Dietrich Brandis, for advice, and made him the first Inspector General of Forests of India.
• Rules about the use of forest resources had to be framed. Brandis set up the Indian Forest Service in 1864 and helped to formulate the Indian Forest Act of 1865.
• The Imperial Forest Research Institute was set up at Dehradun in 1906. The system they taught here was called scientific forestry.
• In scientific forestry, natural forests which had lots of different types of trees were cut down. In their place, one type of tree was planted in straight rows. This was called as plantation.
• The Indian Forest Act, 1878 divided forests into three categories : reserved, protected and village forests. The best forests were called ‘reserved forests’. Villagers could not take anything from these forests. For house building or fuel, they could take wood from protected or village forests.

→ How were the Lives of People Affected

• The Forest Act meant severe hardship for villagers across the country. After the Act, all their everyday practices cutting wood for their houses, grazing their cattle, collecting fruits and roots, hunting and fishing became illegal. It was also common for police constables and forest guards to harass people by demanding free food from them.

→ How did Forest Rules affect Cultivation

• One of the major impacts of European colonialism was on the practice of shifting cultivation. European foresters regarded this practice as harmful for the forests. Therefore, the government decided to ban shifting cultivation. As a result, many communities were forcibly displaced from their homes in the forests.

→  Who Could Hunt

• The customary practice of hunting was prohibited by the forest laws. Those who were caught hunting were now punished for poaching.
• Under colonial rule, the scale of hunting increased largely, and as a result, many animals became almost extinct.

→ New Trades, New Employments and New Services

• While people lost out in many ways after the forest department took control of the forests, some people benefitted from the new opportunities that had opened up in trade. Many communities left their traditional occupations and started trading in forest products.
• In India, trade in forest products was a regular practice since the medieval period.
• The British government gave sole right to large European trading firms to trade in forest products of particular areas.

→ Rebellion in the Forest

• In many parts of India and the world, forest communities rebelled against the changes imposed on them.
• In India, Siddhu and Kanu of Santhal paraganas, Birsa Munda of Chhota Nagpur, Alluri Sitarama Raju of Andhra Pradesh revolted against the new forest policy. They are still remembered today in many songs and stories.

→ The People of Bastar

• Bastar is located in the southern most part of Chhattisgarh and borders of Andhra Pradesh, Odisha and Maharashtra.
• A number of different communities live in Bastar such as Maria and Muria Gonds, Dhurwas, Bhatras and Halbas.
• The people of Bastar believe that each village was given its land by the earth, and in return, they look after the earth by making some offerings at each agricultural festival.

→  The Fears of the People

• When the colonial government proposed to reserve two-thirds of the forest in 1905, and stop shifting cultivation, hunting and collection of forest produce, the people of Bastar were very worried. They began to gather and discuss their issues in their village councils.
• Every village contributed something to the rebellions’ expenses. Bazaars were looted, the houses of officials and traders, schools and police stations were burnt and robbed and grain redistributed.
• The British sent troops to suppress the rebellion. It took three months for the British to regain control.
• In a major victory for the rebels, work on reservation was temporarily suspended and the area to be reserved was reduced to roughly half of that planned before 1910.

→ Forest Transformations in Java

• There were many similarities in the laws for forest control in Indonesia and India. Java is a place in Indonesia where the Dutch started forest management. Like the British, they also wanted timber from Java for ship building.

→ The Wood Cutters of Java

• The Kalangs of Java were a community of skilled forest cutters and shifting cultivators. When the Dutch began to gain control over the forests in the eighteenth century, they tried to make the Kalangs work under them. In 1770, the Kalangs resisted by attacking a Dutch fort at Joana, but the uprising was suppressed.

→ Dutch Scientific Forestry

• In the nineteenth century, when it became important to control territory and not just people, the Dutch enacted forest laws in Java, restricting villagers’ access to forests.
• The Dutch first imposed rents on land being cultivated in the forest and then exempted some villages from these rents if they worked collectively to provide free labour and buffaloes for cutting and transporting timber. This was known as the blandongdiensten system.

→ Samin’s Challenge

• Around 1890, Surontiko Samin of Randublatung village, began questioning the state ownership of the forest. Soon, a widespread movement developed.

→ War and Deforestation

• The First World War and the Second World War had a major impact on forests. In Java, just before the Japanese occupied the region, the Dutch followed a ‘scorched earth’ policy, destroying sawmills, and burning huge piles of giant teak logs so that they would not fall into Japanese hands.
• After the war, it was difficult for the Indonesian forest service to get their land back.

→ New Development in Forestry

• Since the 1980s, governments across Asia and Africa have begun to see that scientific forestry and the policy of keeping forest communities away from forests have resulted in many conflicts.
• Conservation of forests rather than collecting timber has become a more important goal.
• Local forest communities and environmentalists are thinking of different forms of forest management.

→ Important Dates and Related Events

• 1775: Split of Mataram kingdom of Java.
• 1770: The Kalangs attack a Dutch fort at Joana in Java.
• 1864: Setting up of the Indian Forest Service.
• 1875: Enactment of the Indian Forest Act.
• 1878: Amendment to Indian Forest Act.
• 1890: Surontiko Samin of Randublatung village questioned the state ownership of forest.
• 1899-190: Terrible famine in Bastar.
• 1905: Government proposal to reserve two-thirds of the forests.
• 1906: Setting up of the Imperial Forest Research Institute at Dehradun.
• 1907-08: Famine in Bastar, again.
• 1910: Rebellion in Bastar.
• 1927: Amendment to the Indian Forest Act.

→ Colonialism: The policy or practice of a wealthy or powerful nation’s maintaining or extending its control over other countries, especially in establishing settlements or exploiting resources.

→ Deforestation: Refers to the disappearance of forests.

→ Afforestation: Development and cultivation of new forest lands.

→ Aboriginal Communities: Native communities of any place.

→ Sleepers: Wooden planks laid across railway tracks; they hold the tracks in position.

→ Scientific Forestry: A system of cutting trees controlled by the Forest Department in which old trees are cut and new trees are planted in straight rows.

→ Shifting Cultivation: A type of cultivation in which cultivators clear the forests by burning it and use the ash as manure. It is also known as slash and bum technique.

→ Criminal Tribes: Nomadic and pastoralist communities were labelled as criminal tribes because they used to steal wood from the forests.

→ Devsari or Dand or Man: A small token fee paid by the people of one village to the people of other village of Bastar in exchange of wood.

→ Blandongiensten System: This system was introduced by the Dutch in Java under which some villages were exempted from the taxes in terms of free labour and animals for cutting and transportating timber from forests.

→ Dietrich Brandis: A German expert on forests who became the first Inspector General of Forests in India.

→ Alluri Sitaram Raju: Leader of the forest community in Andhra Pradesh

JAC Class 9 Social Science Notes

JAC Jharkhand Board Class 6th Solutions in Hindi & English Medium

• JAC Class 6 Maths Solutions
• JAC Class 6 Science Solutions
• JAC Class 6 Social Science Solutions
• JAC Class 6 English Solutions
• JAC Class 6 Hindi Solutions
• JAC Class 6 Sanskrit Solutions
• JAC Class 6 Social Science Notes

JAC Board Class 9th Social Science Notes History Chapter 3 Nazism and the Rise of Hitler

→ Introduction

• Nazism was a political ideology which flourished in Germany and influenced politics all over the world.
• In May 1945, Germany surrendered to the Allies. Anticipating what was coming, Hitler, his propaganda minister Goebbels and his entire family committed suicide collectively in his Berlin bunker in April.
• When genocidal war started in Germany under the shadow of the Second World War, it caused killings of millions of people in different inhuman ways.

→ Birth of the Weimar Republic

• Germany was a powerful empire in the early 20th century.
• Germany fought the First World War (1914-18) alongside the Austrian empire and against the Allies (England, France and Russia).
• Germany made initial gains in the war by occupying France and Belgium. The Allies were strengthened by the entry of the United States of America (US) in 1917. They defeated Germany and the central powers in November, 1918.
• The defeat of imperial Germany and the resignation of the emperor gave an opportunity to Parliamentary Parties to recast German polity.
• A National Assembly met at Weimar and established a democratic constitution with a federal structure.
• Deputies were elected to the German Parliament or Reichstag on the basis of equal and universal votes cast by all adults including women.
• The peace treaty at Versailles with the Allies was a harsh and humiliating peace for Germany. So, the Weimar Republic had to face too many difficulties since its beginning.

→ The Effect of the War

• The First World War had a devastating impact on the entire continent, both psychologically and financially. The Weimar Republic carried the burden of war guilt and national humiliation and was financially crippled by being forced to pay compensation.
• Socialists, Catholics and democrats who supported the Weimar Republic were criticised and came to be known as ‘November Criminals’ by the conservative nationalists.
• After the First World War, soldiers were placed above civilians and the media glorified their trench life. However, the truth was just the opposite. They lived a miserable life in the trenches.
• Aggressive war propaganda, national honour and support grew for conservative dictatorship.
• At that time in Europe, democracy was a young and fragile idea which could not survive the in stabilities of inter war.

→ Political Radicalism and Economic Crises

• The birth of the Weimar Republic coincided with the revolutionary uprising of the Spartacist League.
• Spartacist League was based on the pattern of the Bolshevik Revolution in Russia.
• The Weimar Republic crushed the uprising of the Spartacist League with the help of the war veterans organisation called the Free Corps.
• The Spartacists later founded the Communist Party of Germany.
• Germany had fought the war largely on loans and had to pay the war reparations in gold.
• With too much printed money in circulation, the value of the German mark fell, which brought hyperinflation in Germany.
• At last, the Americans introduced the Dawes Plan. It helped Germany to overcome the crisis.

→ The Year of Depression

• During the years of Depression (1924-1928), fearing a fall in prices, people made frantic efforts to sell their shares. On one single day, i.e., 24 October, 13 million shares were sold. This was the start of the Great Economic Depression. Over the next three years, between 1929 and 1932 the national income of the USA fell by half.
• The German economy was the worst hit by the economic crisis. The number of unemployed touched an unprecedented 6 million. The economic crisis created deep anxiety and fear in people.
• The Government failed to control the crisis and people lost confidence in the democratic parliamentary system.

→ Hitler’s Rise to Power

• This crisis in the economy, polity and society, formed the background to Hitler’s rise to power. The German defeat horrified him and the Versailles Treaty made him furious. In 1919, he joined a small group called the German Workers Party. Later’ he took over the organisation and the party came to be known as the Nazi Party.
• In 1928, the Nazi Party got only 26 percent votes in the elections to the Reichstag, the German parliament. By 1932, it had become the largest party with 37 percent votes.
• Hitler was a powerful speaker. His passionate speeches about the fatherland and prom¬ises inspired German people.
• Nazi propaganda skillfully projected Hitler as a messiah, a saviour, as someone who had arrived to help German people in a time of acute economic and political crisis.

→ The Destruction of Democracy

• On 30 January, 1933, President Hindenburg offered the Chancellorship to Hitler. Hav¬ing acquired power, Hitler set out to dismantle the structure of democratic rule.
• On 3 March, 1933, the famous Enabling Act was passed. This Act established dictatorship in Germany. It gave Hitler all powers to sideline the Parliament and rule by decree.
  Reconstruction

→ Reconstruction

• Hitler assigned the responsibility of economic recovery to the economist Hjalmar Schacht who aimed at full production and full employment through a state funded work creation programme.
• This project produced the famous German super highways and the people’s car, the Volkswagen.
• In foreign policy, Hitler acquired quick successes.
• Hitler pulled out of the League of Nations in 1933 and reoccupied the Rhineland in 1936.
• In 1938, under the slogan “one people, one empire and one leader”, Austria and Germany were integrated by Hitler.
• Hitler chose war as the way out of the approaching economic crisis.
• In September 1939, Germany invaded Poland and this started a war with France and England.
• In September 1940, a Tripartite Pact was signed between Germany, Italy and Japan.
• Hitler attacked the Soviet Union in June 1941. It was a historic mistake made by Hitler.
• The Soviet Red army defeated Germany at Stalingrad.
• In the beginning, the US remained neutral in the Second World War. When Japan extended its support to Hitler and bombed the US base at Pearl Harbour, the US entered the Second World War.
• The Second World War ended in May 1945 with Hitler’s defeat.
• Japan surrendered in August 1945, after the US dropped atomic bombs on Hiroshima and Nagasaki.

→ The Nazi World View

• According to Nazi ideology, there was no equality between people but only a racial hierarchy.
• In this view, blond, blue-eyed, Nordic German Aryans were at the top, while Jews were located at the lowest rung. All other coloured people were placed in between, depending upon their external features.
• The other aspect of Hitler’s ideology related to the geo-political concept of Lebensraum, or living space.
• Hitler intended to extended the German boundaries by moving eastwards, to concentrate all the Germans geographically in one place. Poland became the laboratory for this experimentation.
  Establishment of the Racial State

→ Establishment of the Racial State

• To implement their plan, the Nazis wanted to eliminate all those who were seen as ‘undesirable’. Nordic Aryans alone were considered ‘desirable’.Only they were seen as worth of prospering and multiplying against all others who .were classed as ‘undesirable’.
• Jews remained the worst sufferers in nazi Germany. They were often persecuted through periodic organised violence, and expulsion from the land.

→ The Racial Utopia

• Under the shadow of war, the Nazis proceeded to realise their murderous, racial ideal. Genocide and war became two sides of the same coin.
• With some of the largest ghettos and gas chambers, the general government also served as the killing fields for the Jews.

→  Youth in Nazi Germany

• Hitler felt that a strong Nazi society could be established only by teaching children, Nazi ideology. All schools were ‘cleansed’ and ‘purified’. This meant, that teachers who were Jews or seen as ‘politically unreliable’ were dismissed. All undesirable children are thrown out of schools, and finally in 1940, all undesirables were taken to the gas chambers.
• The youth league of the Nazis was founded in 1922. Four years later, it was renamed as Hitler Youth.

→ The Nazi Cult of Motherhood

• In Nazi Germany, girls had to maintain the purity of the race. They had to distance themselves from Jews, look after homes and teach their children Nazi values.
• Those mothers who produced racially desirable children were awarded.
• Women who maintained contacts with Jews, Poles or Russians were punished or imprisoned.
  The Art of Propaganda

→ The Art of Propaganda

• The Nazi regime used language and media with care, and often to great effect. Nazis never used the words ‘kill’ or ‘murder’ in their official communication.
• Mass killings were termed as special treatment, final solution, euthanasia, selection and disinfection.
• Media was carefully used to win support for thejregime and popularise its worldview.

→ Ordinary People and the Crimes Against Humanity

• Many ordinary people genuinely believed Nazism would bring prosperity and improve general well-being.
• But not every German was a Nazi, many organised active resistance to Nazism, braving police repression and death.

→ Knowledge about the Holocaust

• Some of the horrible practices followed by Nazis.
• It was only after the war ended and Germany was defeated, that the world came to realise the horror of what had happened. The Jews wanted the world to remember the killings and sufferings they had endured during the Nazi killing operations, also called the ‘Holocaust’.
• Yet the history and the memory of the Holocaust live on in memoirs, fiction, documen¬taries, poetry, memorials and museums in many parts of the world today.

→ Important Dates and Related Events

• August 1,1914: Beginning of the First World War.
• November 9,1918: Germany and the Central Powers defeated in First World War, Weimar Republic establised.
• June 28, 1919: Treaty of Versailles.
• 1922: Nazi youth league founded (later renamed as Hitler Youth).
• 1923: Germany goes through economic crisis and hyperinflation; France, occupies the Ruhr, Germany’s coal mines area.
• 1929: I all Street Exchange in USA crashes.
• 1932: Nazi party becomes the largest party in Reichstag-the German Par. ‘ment.
• 1929-1932: Great Depression, National Income of USA fell by half.
• January 30, 1933: Hitler bec.’me Chancellor of Gtrmany.
• February 28: Fire Decree declared in Germany:
• March 3, 1933:Enabling Act passed, establishing Hitler’s dictatorship.
• 1933: Germany pulls out of the league of Nations.
• 1938: Germany and Austria integrated.
• September 1, 1939: Germany invaded Poland. Beginning of the Second World War.
• September, 1940: Tripartite pact between Germany, Italy and Japan signed.
• June 22,1941: Germany invaded the USSR.
• June 23, 1941: Beginning of mass murder of the Jews.
• December 8,1941: The USA joined Second World War.
• 1940-1944: Ghettoisation of Jews and their killing in gas chambers.
• January 27, 1945: Soviet troops liberated Auschwitz.
• May 8, 1945: Allied victory in Europe.

→ Allies: The Allied Powers were initially led by the UK and France. In 1941, they were joined by the USSR and USA. They fought in the Second World War against the Axis Powers, namely-Germany, Italy and Japan.

→ Genocidal: Killing on large scale leading to destruction of large sections of people.

→ Reichstag: Name of the German Parliament.

→ Free Corps: A war veterans organisation.

→ Reparation: Make up for a wrong done.

→ Deplete: Reduce, empty out.

→ Hyper Inflation: A very high rise in prices.

→ Wall Street Exchange: The name of the world’s biggest stock exchange located in the USA.

→ Proletarianisation: To become impoverished to the level of working classes.

→ Propaganda: Specific type of message directly aimed at influencing the opinion of people (through the use of posters, films, speeches, etc.)

→ Decree: An official order forced by law.

→ Nazis: Short form of National Socialist German Worker Party members.

→ Swastika: Symbol of Nazis.

→ Concentration Camp: A camp where people were isolated and detained without due process of law. Typically, it was surrounded by electrified barbed wire fences.

→ Gestapo: Secret state police of Germany.

→ Lebensraum: A living space.

→ Persecution: Systematic, organised punishment of those belonging to a group or religion.

→ Usurers: Moneylenders charging excessive rate of interest; often used as a term of abuse.

→ Ghettos: A separately marked area for the Jews where they could live.

→ Pauperised: Reduce to absolute poverty.

→ Synagogues: Place of worship for people of Jewish faith.

→ Jungvolk: Nazi youth groups for children below 14 years of age.’

→ Holocaust: Sufferings and atrocities that people had to bear during the Nazi killing operations.

→ Security Device: Secret state policy.

→ Nuremberg: The place where an International Military tribunal was set up at the end of the Second World War to prosecute Nazi criminals.

→ Jew: A person whose religion is Judaism.

→ Gypsy: The groups that were classified as ‘Gypsy’ had their own community identity. Sinti and Roma were two such communities.

→ Nordic German Aryans: One branch of those classified as Aryans. They lived in north European countries and had German or related origin.

→ Adolf Hitler: The central figure in post First World War Germany, set up the most dreaded military rule.

→ Goebbles: Propaganda minister of Hitler.

→ Hjalmar Schacht: Economist who was assigned the responsibility of making a plan for economic recovery of Germany.

→ Charles Darwin: A natural scientist who tried to explain the creation of plants and animals through the concept of evolution and natural selection.

→ Charlotte Beradt: Author of the Third Reich of Dreams.

JAC Class 9 Social Science Notes

JAC Jharkhand Board Class 7th Solutions in Hindi & English Medium

• JAC Class 7 Maths Solutions
• JAC Class 7 Science Solutions
• JAC Class 7 Social Science Solutions
• JAC Class 7 English Solutions
• JAC Class 7 Hindi Solutions
• JAC Class 7 Sanskrit Solutions
• JAC Class 7 Social Science Notes

JAC Board Class 9th Science Important Questions Chapter 13 Why Do We Fall Ill

Multiple Choice Questions

Question 1.
The disease that affects our lungs is
(a) jaundice
(b) tuberculosis
(c) scabies
(d) herpes
Answer:
(b) tuberculosis

Question 2.
The BCG vaccine provides immunity against
(a) dengue
(b) influenza
(c) ebola
(d) tuberculosis
Answer:
(d) tuberculosis

Question 3.
Malaria is caused by
(a) Anopheles mosquito
(b) Bacteria
(c) Protozoa
(d) Virus
Answer:
(a) Anopheles mosquito

Question 4.
Trypanosoma, Leishmania and Plasmodium are the examples of
(a) protozoa
(b) worms
(c) fleas
(d) viruses
Answer:
(a) protozoa

Question 5.
Diarrhoea, cholera, typhoid are the diseases that have one thing in common, which is
(a) all of them are air-borne
(b) all of them are caused by a virus
(c) all of them are caused by contaminated food and water
(d) all of them cause headache
Answer:
(c) all of them are caused by contaminated food and water

Question 6.
HIV virus attacks which one of the following cells in our body?
(a) Liver cells
(b) Neurons
(c) Nephrons
(d) White blood cells
Answer:
(d) White blood cells

Question 7.
Pathogens of disease are
(a) viruses
(b) bacteria
(c) protozoa
(d) all of the above
Answer:
(d) all of the above

Question 8.
Which of the following is a worm – caused disease?
(a) Herpes
(b) Filariasis
(c) Rabies
(d) Conjunctivitis
Answer:
(b) Filariasis

Question 9.
Which of the following is not a viral disease?
(a) AIDS
(b) Rabies
(c) Polio
(d) Tuberculosis
Answer:
(b) Rabies
(d) Tuberculosis

Question 10.
Which of the following is caused by Plasmodium parasite?
(a) Hepatitis
(b) Jaundice
(c) Tuberculosis
(d) Malaria
Answer:
(d) Malaria

Analysing & Evaluating Questions

Question 11.
If you live in an overcrowded and poorly ventilated house, you may probably suffer from which of the following diseases?
(a) Cancer
(b) AIDS
(c) Air-borne diseases
(d) Cholera
Answer:
(c) Air – borne diseases

Question 12.
During infection or injuries, inflammation of body organs occurs due to the activation of
(a) nerves
(b) muscles
(c) immune system
(d) breathing
Answer:
(c) immune system

Question 13.
Suppose you are experiencing the symptoms of cough and breathlessness. Which organ of your body do you think might be affected?
(a) Kidney
(b) Lung
(c) Heart
(d) Stomach
Answer:
(b) Lung

Assertion-Reason Questions

Directions. In the following questions, the Assertions and the Reasons have been put forward. Read the statements carefully and choose the correct alternative from the following.
(A) Both the assertion and the reason are correct and the reason is the correct explanation of the assertion.
(B) The assertion and the reason are correct but the reason is not the correct explanation of the assertion.
(C) The assertion is true but the reason is false.
(A) Both the assertion and the reason are correct and the reason is the correct explanation of the assertion.

1. Assertion: DPT is a triple antigen.
Reason: DPT is administered against three diseases namely diphtheria, pertussis and tetanus.
Answer:
(A) Both the assertion and the reason are correct and the reason is the correct explanation of the assertion.

2. Assertion: Antibiotics are effective against both the bacteria and the viruses.
Reason:  Viruses have many biochemical mechanisms of their own.
Answer:
(A) Both the assertion and the reason are correct and the reason is the correct explanation of the assertion.

3. Assertion: Male Anopheles mosquitoes do not spread malaria.
Reason: Male Anopheles mosquitoes do not feed on human blood.
Answer:
(A) Both the assertion and the reason are correct and the reason is the correct explanation of the assertion.

4. Assertion: Typhoid spreads through contaminated food and water.
Reason: Typhoid can never become an epidemic in a locality.
Answer:
(C) The assertion is true but the reason is false.

5. Assertion: HIV attacks the immune system of a person.
Reason: HIV is responsible for AIDS in people infected with it.
Answer:
(B) The assertion and the reason are correct but the reason is not the correct explanation of the assertion.

Very Short Answer Type Questions

Question 1.
What do you understand by symptoms of a disease?
Answer:
Symptoms are the signs of a disease which indicate the presence of that particular disease.

Question 2.
What are acute diseases?
Answer:
Acute diseases are diseases that last for a very short period of time.

Question 3.
What are chronic diseases?
Answer:
Chronic diseases are diseases that last for a very long period of time.

Question 4.
What are infectious diseases?
Answer:
Infectious diseases are diseases that can spread from an infected person to another healthy person, e. g., ebola.

Question 5.
Name any one disease caused due to genetic abnormality.
Answer:
Sickle-cell anaemia.

Question 6.
Name two diseases caused by protozoa.
Answer:
Trichomoniasis and malaria.

Question 7.
Name two diseases each caused by bacteria, viruses and fungi.
Answer:
Bacteria – typhoid, cholera; Viruses – ebola, mumps; Fungi – Jock-itch, ringworm.

Question 8.
Write the full form of AIDS.
Answer:
Acquired Immunodeficiency Syndrome.

Question 9.
Which organism causes sleeping sickness?
Answer:
A protozoan called Trypanosoma causes sleeping sickness.

Question 10.
Name the causative agent of kala – azar?
Answer:
Leishmania.

Question 11.
Name two air-borne diseases.
Answer:
Anthrax and smallpox.

Question 12.
Name two organ specific diseases.
Answer:
Autoimmune hepatitis which affects the liver and Grave’s disease which affects the thyroid.

Question 13.
Which virus is responsible for AIDS?
Answer:
HIV virus is responsible for AIDS.

Question 14.
State the organs affected by the following diseases. jaundice, malaria, typhoid.
Answer:
Jaundice: liver; malaria – liver and RBCs; typhoid – infects the blood.

Question 15.
How do we kill microbes that enter our bodies?
Answer:
We kill disease: causing microbes with the help of medicines that block the synthesis pathways of microbes.

Question 16.
What are disease specific means of prevention?
Answer:
Disease specific means of prevention is the use of vaccine which prevents specific diseases from affecting us, e.g., tetanus vaccine, rabies vaccine, etc.

Question 17.
Why is the creation of antiviral drugs hard?
Answer:
Viruses grow inside the host and use the host cell machinery and pathways for all its biological processes. Hence, antibiotics are not able to target the virus-specific pathways. Moreover, viruses can alter their mechanisms at a very high rate, so it becomes difficult to target a specific mechanism.

Analysing & Evaluating Questions

Question 18.
Suppose your friend is suffering from severe cold and it makes him sneeze frequently heavily. What would you suggest him as a precautionary measure so that you do not become infected with the disease?
Answer:
Severe cold or cough are airborne diseases which spread through inhalation of respiratory droplets that are released by sneezing and coughing by an infected individual. Therefore, I would suggest my friend to cover his mouth while sneezing or coughing so that virus responsible for causing this disease does not infect others.

Question 19.
A person is suffering from fever and headache from quite a period of time. He is suspecting that it may be typhoid. What should he do to confirm whether it is the same disease?
Answer:
Confirmation of a particular disease can be done by undergoing proper medical check up and laboratory tests under the supervision of a doctor.

Question 20.
Suppose a person is suffering from jaundice. Whether prescribing him penicillin will be useful or not? Name the target organ for jaundice.
Answer:
No, penicillin would not be useful in the treatment of jaundice because it is a viral diseases. Target organ for jaundice is liver.

Short Answer Type Questions

Question 1.
Define health, disease, pathogens and antibiotics.
Answer:
Health. It is a state of mental, physical and social well-being.
Disease. It is the deviation from the normal healthy well-being of an individual.
Pathogens. They are disease-causing microbes, e.g., bacteria, worms, fungi, etc.
Antibiotics. These are drugs that block the biochemical pathways important to bacteria, thereby killing them.

Question 2.
What are the two main causes of a disease?
Answer:
The two main causes are immediate and contributory causes. Immediate cause-this is due to pathogens entering our bodies. Contributory cause-these are the secondary factors which allow these pathogens to enter our bodies through dirty water, contaminated food, infected surroundings, etc.

Question 3.
Define and give examples of vaccines.
Answer:
Vaccine is an antigenic substance prepared from the agent causing the disease, which is given in advance to a body to provide immunity against that specific disease, e.g., chickenpox vaccine, hepatitis vaccine, polio vaccine.

Question 4.
What is antibiotic penicillin? Give its function.
Answer:
Penicillin is a drug prepared from the fungus Penicillium, which does not allow bacteria to build its protective cell wall, thus it dies off easily. It is used to cure diseases and infections caused by bacteria.

Question 5.
A bacterium is a cell which is destroyed by an antibiotic. Our body is also made up of cells. How come antibiotics do not affect our bodies as well?
Answer:
An antibiotic blocks the biochemical pathway through which bacteria build a protective cell wall. Human body cells do not have this cell wall, so antibiotics cannot have any such effect on our body.

Question 6.
How can cholera become an epidemic in a locality?
Answer:
Cholera is a communicable disease that spreads through contaminated water and food. Let’s say, a person living in a locality contaminates the local water supply with cholera through his excreta. Now, all the people of that locality who drink that water will get infected with cholera.

Question 7.
Why are sick patients asked to take bed rest?
Answer:
Sick patients are asked to take bed rest so that they can conserve their energy which can be used to heal their recovering organs. Moreover, if they move around, there are higher chances of them getting infected with other diseases as their immune system is already weak.

Question 8.
Write a short note on malaria, its symptoms and control.
Answer:
Malaria is caused by a protozoan that lives in blood. The parasite enters our bodies when a female Anopheles mosquito, having the protozoa named Plasmodium, sucks our blood. This protozoan affects our liver and blood cells.

• Symptoms: muscular pain, headache and very high fever.
• Control: keeping the surroundings clean with no stagnant water, using mosquito repellents, use of quinine drug.

Question 9.
What is AIDS? How does a person contract AIDS?
Answer:
AIDS or Acquired Immunodeficiency Syndrome is a disease caused by the Human immuno deficiency virus. A person with AIDS has severely affected immune system. Hence, he or she dies from other diseases that thrive from the lack of Acquired WBCs in the HIV infected body.
A person contracts AIDS in the following ways:

1. Blood transfusion
2. Sexual intercourse
3. From infected mother to a baby (in the womb)
4. Sharing of needles with infected people
5. Breast feeding (if the feeder is infected).

Question 10.
Becoming infected by an infectious microbe does not always develop into a disease. Why?
Answer:
This is because our immune system is always active and when foreign particles (microbes) enter our body, the immune system instantly attacks it, trying to kill it. So, in cases where our immune system is successful in killing the infectious microbe, we don’t develop the disease it was supposed to cause.

Question 11.
(a) Why is a balanced diet necessary for maintaining a healthy body?
(b) Name two diseases caused by junk food.
Answer:
(a) A balanced diet provides all the nutrients required by our body in the correct amount. It helps to keep our immune system healthy,

(b) Two diseases caused by junk food are obesity and high blood pressure.

Analysing & Evaluating Questions

Question 12.
No polio cases have been reported from India since the last three years. On that basis, WHO has presented certification of poliofree status to India.
1. Which pathogen is responsible for causing polio in children?
2. How the principle of immunisation is implemented for eliminating polio?
3. What is OPV?
Answer:

1. Poliomyelitis virus.
2. Oral vaccines for polio are given periodically to children under five years to age to eliminate the occurrence of the disease. These vaccines are the preparations of weak forms of polio virus strains. These preparations stimulate the body to produce antibodies in response to the exposure to polio viruses. Thus, body becomes immune to the polio disease.
3. Oral Polio Vaccine.

Question 13.
Sachin’s younger brother was suffering from diarrhoea and vomiting. So he made Oral Rehydration Solution (ORS) and gave it to his brother to drink frequently. Then he thought to take him to the doctor for medical checkup.
1. What may be the cause of diarrhoea and vomiting?
2. Name the causative agents for these diseases?
3. Why Sachin gave ORS to his brother?
Answer:

1. Diarrhoea and vomiting may occur due to the consumption of contaminated food and water.
2. The causative agents for these are mainly bacteria, but some protozoa and viruses can also cause diarrhoea and vomiting.
3. Due to diarrhoea and vomiting, the body loses excess of water and other salts leading to dehydration of the body. Therefore, Sachin used his knowledge to save his brother from the discomfort of dehydration by giving him ORS.

Long Answer Type Questions

Question 1.
If someone in the family gets an infectious disease, what precautionary steps will you take to help that person recover fast and prevent other family members from getting infected?
Answer:
(a) The infected person should be kept isolated in a separate room.
(b) The surroundings and the house need to be kept clean.
(c) His (the patient) clothes and utensils should be sanitised regularly.
(d) Separate towels, sheets and blankets should be used by the patient.
(e) Clean and boiled drinking water should be given to the patient.
(f) A balanced and nutritious meal should be provided to the patient.
(g) The patient should be allowed enough rest to recover fully.

Question 2.
What are the different methods used for the treatment and prevention of diseases?
Answer:
Principles of treatment for diseases are:
(a) To reduce the symptoms of the disease.
(b) To kill the cause of the disease, i.e., to kill the disease-causing microbes like bacteria, fungi, protozoa.

Principles of prevention are:
(a) General ways: It relates to preventing exposure to the microbes, which can be done in the following ways.

1. For air – borne infections. Avoid public spaces, cover your nose while coughing and sneezing.
2. For water – borne infections. Drink safe and filtered water.
3. For vector – borne diseases. Keep the surroundings clean, cover your food and water, do not allow stagnant water to collect.
4. Self – immunity. Exercise regularly to keep your immune system strong.

(b) Specific ways: By getting vaccination, regular checkups and medications.

Question 3.
State the mode of transmission for the following diseases. malaria, AIDS, jaundice, typhoid, cholera, rabies, tuberculosis, diarrhoea, hepatitis, influenza.
Answer:

Disease	Mode of transmission
1. Malaria	Mosquito bite (female Anopheles mosquito)
2. AIDS	Infected blood, semen, mother’s milk, sharing needle of an infected person
3. Jaundice	Contaminated water
4. Typhoid	Contaminated food and water
5. Cholera	Contaminated food and water
6. Rabies	Bite of a rabid animal
7. Tuberculosis	Cough and sneeze droplets
8. Diarrhoea	Contaminated food and water
9. Hepatitis	Contaminated food and water
10. Influenza	Cough and sneeze droplets

Question 4.
(a) What causes chickenpox?
(b) State a few precautionary measures for it.
Answer:
(a) Chickenpox is caused by a virus called varicella-zoster virus,
(b) Some precautionary steps for chicken pox are.

• The infected person should avoid direct contact with people.
• His clothes should be soaked in boiling water before washing so as to kill the virus.
• Vaccination should be taken in advance to prevent the disease.

Analysing & Evaluating Questions

Question 5.
Children living in slum areas frequently suffer from symptoms such as abdominal pain, diarrhoea, loose motions, vomiting and loss of appetite.
(a) Name the target organ or organ system for the occurrence of these symptoms.
(b) Why children are frequently suffering from these symptoms?
(c) What should be done to improve the health status of these children?
Answer:
(a) The target organ or organ system for the occurrence of these symptoms is alimentary canal.

(b) These symptoms appear frequently in the children because they live in unhygienic environment where there is non availability of clean drinking water. Hence, making them prone to infections of alimentary canal.

(c) The local authorities responsible for providing public health services should be informed regarding these health problems in the children. There should be provision of clean drinking water supply and proper sanitation in the area, so that the spread of water-borne infections can be prevented.

Activity 1

• Find out what provisions are made by your local authority (Panchayat/ Municipal Corporation) for the supply of clean drinking water.
• Find out if all the people in your locality are able to access this.

Observations:

• Local authority, i.e., Municipal Corporation of our area recycles the water. Used water is treated in water treatment plants, chlorinated and supplied through pipes to people. Water taken from river is also cleaned and made potable.
• People, who live outside municipal limits use underground water, which is supposed to be safe, by drawing water through handpumps, wells and tube-wells.

Activity 2

• Rabies virus is spread by the bite of infected dogs and other animals. There are anti-rabies vaccines for both humans and animals.
• Find out the plan of your local authority for the control of rabies in your neighbourhood. Also find if these measures are adequate or not. Suggest some improvements.

Observations:

• Local authorities have plan to provide free anti-rabies vaccination at health centres, dispensaries, etc., and also catch the stray dogs. But animal loving organisations force to let them free. Pet owners are required to get anti-rabies vaccination to their dogs/ cats. But this rule is not strictly followed.
• Suggestions.
  • People should be educated through campaigns about anti-rabies vaccination for both humans and animals.
  • Stray dogs/cats/other animals should be provided with anti-rabies vaccination.
  • Pet owners should be strictly instructed to get themselves and their pets vaccinated against rabies.

Value Based Questions

Question 1.
Radha’s brother, who is 5 years old, had high fever for two days. Doctor prescribes him antibiotics. Radha hesitantly asks for the name of the disease his brother had and why he was advised to take antibiotics without any diagnosis.
1.  Is fever a disease?
2. What is the role of antibiotics?
3. What values of Radha are reflected in the above act?
Answer:

1. Fever is not a disease; it is a symptom.
2. Antibiotics are medicines advised to be taken only when the immune system of a patient is unable to fight against the microbes.
3. Radha showed moral responsibility and general awareness.

Question 2.
Jyoti was suffering from chickenpox and was advised to stay at home by her doctor. Jyoti’s friend persuades her to go for class picnic along with her and have fun. But Jyoti refuses and stays at home.
1. What is the cause of chickenpox?
2. Give one precaution for it.
3. What value of Jyoti is reflected in not going for picnic?
Answer:

1. Virus causes chickenpox.
2. One precaution for avoiding spread of chickenpox is to stay away from public places when one is suffering from it and take vaccination.
3. Jyoti showed moral responsibility and self-awareness.

JAC Class 9 Science Important Questions

JAC Board Class 9th Science Important Questions Chapter 12 Sound

Multiple Choice Questions

Question 1.
Which part of the human ear converts sound vibrations into electrical signals?
(a) Malleus
(b) Incus
(c) Tympanic membrane
(d) Cochlea
Answer:
(d) Cochlea

Question 2.
What do dolphins, bats, and tortoises use to hear the sound?
(a) Ultrasound
(b) Infrasound
(c) Both (a) and (b)
(d) None of these
Answer:
(a) Ultrasound

Question 3.
Children under the age of 5 can hear upto
(a) 25 Hz
(b) 25 kHz
(c) 20 Hz
(d) 20 kHz
Answer:
(b) 25 kHz

Question 4.
Multiple reflections of sound are used in
(a) stethoscope
(b) trumpet
(c) megaphone
(d) all of these
Answer:
(d) all of these

Question 5.
To hear a distinct echo, the time interval between the original sound and the reflected sound must be at least
(a) 0.2s
(b) 1s
(c) 2s
(d) 0.1s
Answer:
(d) 0.1s

Question 6.
Speed (v), wavelength (l) and the frequency (v) of a sound wave are related as
(a) λ = v × λ
(b) v = λ – v
(c) v = λ × v
(d) v = λ/v
Answer:
(c) v = λ × v

Question 7.
Speed of sound depends upon
(a) temperature of the medium
(b) density of the medium
(c) temperature of source producing sound
(d) temperature and density of the medium
Answer:
(d) temperature and density of the medium

Question 8.
Using which characteristic of sound can we distinguish between the sounds having same pitch and loudness?
(a) Tone
(b) Note
(c) Pitch
(d) Timber
Answer:
(d) Timber

Question 9.
Loud sound can travel a larger distance, due to
(a) higher amplitude
(b) higher energy
(c) higher frequency
(d) higher speed
Answer:
(a) higher amplitude

Question 10.
A wave in slinky travelled to and fro in 5 s. The length of the slinky is 5 m. What is the velocity of the wave?
(a) 10 m/s
(b) 5 m/s
(c) 2 m/s
(d) 25 m/s
Answer:
(b) 5 m/s

Question 11.
The reciprocal of frequency is
(a) amplitude
(b) wavelength
(c) time – period
(d) wave velocity
Answer:
(c) time – period

Question 12.
To and fro motion of an object is called
(a) wave
(b) vibrations
(c) amplitude
(d) all of the above
Answer:
(b) vibrations

Question 13.
Which of the following frequencies will be audible to the human ear?
(a) 5 Hz
(b) 5000 Hz
(c) 27000 Hz
(d) 50000 Hz
Answer:
(b) 5000 Hz

Question 14.
If the distance between a crest and its consecutive trough is L, then the wavelength of the wave is given by
(a) L
(b) 2L
(c) L/2
(d) 4L
Answer:
(b) 2L

Question 15.
What is the nature of the ocean waves in deep water?
(a) Transverse
(b) Longitudinal
(c) Both transverse and longitudinal
(d) None of these
Answer:
(c) Both transverse and longitudinal

Analysing & Evaluating Questions

Question 16.
A key of a mechanical piano is struck gently and then struck again but much harder this time. In the second case
(a) sound will be louder but pitch will not be different
(b) sound will be louder and pitch will also be higher
(c) sound will be louder but pitch will be lower
(d) both loudness and pitch will remain unaffected
Answer:
(a) sound will be louder but pitch will not be different

Question 17.
Which kind of sound is produced by an earthquake before the main shock wave begins?
(a) ultrasound
(b) infrasound
(c) audible sound
(d) none of these
Answer:
(b) infrasound

Question 18.
Before playing the orchestra in a musical concert, a sitarist tries to adjust the tension and pluck the string suitably. By doing so, he is adjusting
(a) intensity of sound only
(b) amplitude of sound only
(c) frequency of the sitar string with the frequency of other musical instruments
(d) loudness of sound
Answer:
(c) frequency of the sitar string with the frequency of other musical instruments

Assertion Reason Questions

Directions: In the following questions, the Assertions and the Reasons have been put forward. Read the statements carefully and choose the correct alternative from the following:
(A) Both the assertion and the reason are correct and the reason is the correct explanation of the assertion.
(B) The assertion and the reason are correct but the reason is not the correct explanation of the assertion.
(C) The assertion is true but the reason is false.
(D) Both the statements are false.
1. Assertion:
Sound travels as a longitudinal wave in air.
Reason: Sound wave needs a medium for its propagation.
Answer:
(B) The assertion and the reason are correct but the reason is not the correct explanation of the assertion.

2. Assertion: Speed of sound increases on increasing the temperature of the medium through which its propagates.
Reason: On increasing the temperature, kinetic energy of the particles of medium increases.
Answer:
(B) The assertion and the reason are correct but the reason is not the correct explanation of the assertion.

3. Assertion: Stage of an auditorium has a curved sound board behind the stage.
Reason: Curved wall spreads sound in all directions evenly.
Answer:
(A) Both the assertion and the reason are correct and the reason is the correct explanation of the assertion.

4. Assertion: Sound travels faster in solids than in liquids.
Reason: Particles of solids are closely packed as compared to those of liquids.
Answer:
(A) Both the assertion and the reason are correct and the reason is the correct explanation of the assertion.

5. Assertion: Pitch of a sound wave depends on its frequency.
Reason: Higher the frequency, lesser is the pitch of the sound wave.
Answer:
(C) The assertion is true but the reason is false.

Very Short Answer Type Questions

Question 1.
What is SONAR?
Answer:
SONAR (Sound Navigation And Ranging) is a technique used for determining water depth and locating underwater objects, such as reefs, submarines and school of fish.

Question 2.
Define one hertz.
Answer:
One hertz is one vibration per second.

Question 3.
Name the two types of mechanical waves.
Answer:
The two types of mechanical waves are:

1. Transverse wave
2. Longitudinal wave

Question 4.
What is a wave?
Answer:
A wave is a disturbance that travels in a medium due to repeated periodic motion of particles about their mean position, such that the disturbance is handed over from one particle to the other without the actual movement of the particles of the medium.

Question 5.
What is a longitudinal wave?
Answer:
It is a wave in which the particles of the medium vibrate in the direction of propagation of the wave.

Question 6.
What is a transverse wave?
Answer:
It is a wave in which the particles of the medium vibrate perpendicular to the direction of propagation of the wave.

Question 7.
What do you understand by the term ‘echo’?
Answer:
The sound heard after reflection from a rigid obstacle back to the listener is called ‘echo’.

Question 8.
What is ‘pitch’?
Answer:
The way our brain interprets the frequency of an emitted sound is called ‘pitch’.

Question 9.
What is ‘note’ of a sound?
Answer:
The sound produced due to a mixture of several frequencies is called a ‘note’.

Question 10.
What are ‘ultrasonic’ and ‘infrasonic’ sound waves?
Answer:
Sound waves with frequencies below the audible range (less than 20 Hz) are termed as ‘infrasonic sound waves’ and sound waves with frequencies above the audible range (more than 20,000 Hz) are termed as ‘ultrasonic sound waves’.

Analysing & Evaluating Questions

Question 11.
The speed of sound in vulcanised rubber is much lower than in the common solids. Give a proper explanation.
Answer:
Rubber is soft, porous and sound absorber.

Question 12.
A sound wave corresponds to larger number of compressions and rarefaction passing through a fixed point per unit of time. Should it have higher pitch or lower pitch?
Answer:
Such a sound wave will have higher pitch, (i.e., higher frequency).

Question 13.
An echo is heard on a day when temperature is about 22°C. Will the echo be heard sooner or later if the temperature falls to 4°C?
Answer:
At lower temperature, the speed of sound will decrease. Therefore, to travel through the same distance, it will take more time. So the echo will be heard later.

Short Answer Type Questions

Question 1.
What are mechanical or elastic waves? Give examples.
Answer:
The waves which require a material medium for their propagation are called f mechanical waves. They are also called elastic waves because their propagation depends on the elastic properties of the medium.

Examples of mechanical waves:
(a) Sound waves in air.
(b) Waves over water surface.
(c) Waves produced during earthquake (seismic waves).

Question 2.
What are electromagnetic waves? Cite examples.
Answer:
The waves which do not require a material medium for their propagation are called electromagnetic waves. Such waves travel through vacuum with a speed of 3 × 108 m/s.
Examples of electromagnetic waves:
(a) Light waves
(b) X – rays
(c) Radio waves
(d) Microwaves

Question 3.
Define ‘crests’ and ‘troughs’ of a wave.
Answer:
In transverse waves, the particles of the medium which have maximum displacement in the positive Y – direction are called ‘crests’ while those which have maximum displacement in the negative Y – direction are called ‘troughs’.

Question 4.
Define the terms ‘compressions’ and ‘rarefactions’.
Answer:
When longitudinal waves pass through a medium, these cause pressure variations in different parts of the medium. The regions of increased pressure are called ‘compressions’ and the regions of decreased pressure are called ‘rarefactions’.

Question 5.
Differentiate between sound and light waves.

Sound wave	Light wave
(a) Travels in the form of longitudinal wave.	(a) Travels in the form of transverse wave.
(b) Requires a medium for its propagation.	(b) Does not require a medium for its propa – gation.
(c) Travels through air with a speed of 332 m/s at 0°C.	(c) Travels through air with a speed of nearly 3 × 108 m/s.

Question 6.
Why are the longitudinal waves also called pressure waves?
Answer:
Longitudinal waves travel in a medium as a series of alternate compressions and rarefactions, i.e., as they travel, there is a variation in pressure across the medium. Therefore, they are called pressure waves.

Question 7.
Derive a relation between wavelength, frequency and velocity of a wave.
Answer:
Frequency, wavelength and wave velocity are related as follows: Wavelength is the distance travelled by the wave during the time a particle of the medium takes to complete one vibration. Therefore, if λ be the wavelength and T be the time – period, the wave travels a distance λ in time T.
Hence, Wave velocity = \(\frac{Distance}{Time}\)
⇒ v = \(\frac{\lambda}{\mathrm{T}}\)
⇒ v = λ v
∵ {\(\frac{1}{T}\) = frequency (v)}
∴ Wave velocity = Frequency × Wavelength
The wave velocity in a medium remains constant under the same physical conditions.

Question 8.
On what factor does the frequency of a wave depend?
Answer:
Frequency of a wave is given by,
v = \(\frac{\mathrm{v}}{\lambda}\)
Where,
v is the speed with which the wave propagates, and λ is the wavelength of the wave. Different sources produce oscillations of different frequencies depending on the wavelength of the sources. Frequency changes such that the speed remains constant.

Question 9.
A boat at anchor is rocked by waves whose consecutive crests are 100 m apart. The wave velocity of the mocking crests is 20 m/s. What is the frequency of rocking of the boat?
Answer:
Wavelength, λ = Distance between two successive crests = 100 m
Velocity, v = 20 m/s
Frequency, v = \(\frac{\mathrm{v}}{\lambda}\) = \(\frac{20}{100}\) = 0.20 Hz.

Question 10.
Why do the animals behave in apeculiar manner before an earthquake?
Answer:
When the earthquake strikes, it produces low frequency infrasounds before the main shock waves. These infrasonic waves are not audible to the human ears. But animals are able to detect these waves and hence some animals get disturbed before earthquakes and start behaving in a different manner.

Question 11.
Differentiate between longitudinal wave and transverse wave.
Answer:

Longitudinal wave	Transverse wave
(a) It needs a medium for propagation.	(a) It may or may not need a medium for propagation.
(b) Particles of the medium move in a direction parallel to the direction of propagation of the disturbance.	(b) Particles of the medium move in a direction perpendicular to the direction of propagation of the disturbance.
Example: Sound wave.	Examples: Light wave and seismic wave.

Question 12.
What are multiple echoes? Give examples.
Answer:
The successive reflection of a sound wave from a number of obstacles results in hearing the echo of the sound transmitted one after the other. When a sound is repeatedly reflected between two parallel distant buildings or cliffs, multiple echoes are produced. For example, rolling of thunder is due to successive reflections between clouds and land surfaces.

Question 13.
A sound wave causes the density of air at a place to oscillate 1200 times in 2 minutes. Find the time period and frequency of the wave.
Answer:
Frequency = \(\frac{1200}{2 \times 60}\) = 10 Hz.
Time period = ?
Frequency = \(\frac{1}{\mathrm{~T}}\)
T = \(\frac{1}{Frequency}\) = \(\frac{1}{10}\) = 0. 1s.

Analysing & Evaluating Questions

Question 14.
The speed of certain waves depends on the source and the medium through which they travel.
1. What kind of waves are these?
2. Give one example of the answer to (a).
Answer:

1. These waves are mechanical waves.
2. Sound waves, water waves, string waves are mechanical waves.

Question 15.
The sound of an explosion on the surface of a lake is heard by a boatman 100 m away and by a diver 100 m below the point of explosion.
1. Who will hear the sound of explosion first?
2. If sound takes time t seconds to reach the boatman, how much time (approximately) will it take to reach the diver?
Answer:
1. The diver who is 100 m below the point of explosion will hear the sound of explosion first because sound travels much faster in water than in air.

2. Time taken by sound to reach the diver
= \(\frac{ Speed of sound in air × t}{Speed of sound in Water }\)
= \(\frac{344 \mathrm{~m} \mathrm{~s}^{-1}}{1533 \mathrm{~m} \mathrm{~s}^{-1}} \times \mathrm{ts}\)
= 0.22 t seconds

Long Answer Type Questions

Question 1.
State the factors on which the speed of sound in a gaseous medium depends.
Answer:
The speed of sound in a gas depends on the following factors:
(a) Effect of density: At constant pressure, the speed of sound in a gas is inversely proportional to the square root of its density.
Speed of sound ∝ = \(\frac{1}{\sqrt{\text { Density of gas }}}\)

(b) Effect of humidity: Sound travels faster in moist air than in dry air.

(c) Effect of temperature: The speed of sound in a gas is directly proportional to the square root of its absolute temperature.
Speed of sound ∝= \(\sqrt{\text { Absolute temperature of gas }}\)
So, the speed of sound increases with the increase in temperature of the gas. For example, the speed of sound in air is 331 ms^-1 at 0°C and 344 ms^-1 at 20°C.

(d) Effect of wind: Sound is carried by air, so the speed of sound increases when the wind blows in the direction of sound and speed of sound decreases when the wind blows in the direction opposite to the direction of sound.

Question 2.
Explain some important applications of ultrasound in industry and medicine.
Answer:
Applications of ultrasound in industry and medicine are as follows:

• Industrial applications:
  1. The construction of big structures like buildings, bridges, machines, scientific equipment, etc., use metallic components.
  2. The cracks or holes inside the block reduce the strength of the structure. Such defects are not visible from outside. Ultrasonic waves can be used to detect such defects.
  3. Ultrasonic waves are allowed to pass through the metal block and detectors are used to detect the transmitted waves. If there is even a small defect, the ultrasound gets reflected back and does not reach the detector. This is how the presence of a flaw or defect is detected.
• Medical applications:

1. Echocardiography: In this technique, ultrasonic waves are made to reflect from various parts of the heart to form the image of the heart.
2. Ultrasonography: Ultrasonic waves can be used to develop three dimensional photographs of different parts of the human body. This technique is called ultrasonography.
   • This technique is also used to monitor the growth of a foetus inside its mother’s womb In this technique, the ultrasonic waves travel through the tissues of the body and get reflected from a region where there is a change of tissue density.
   • These waves are then converted into electrical signals that are used to generate images of the organ. These images are then displayed on a monitor or printed on a film.
3. In surgery: Ultrasonic waves are commonly used in cataract removal. Ultrasonic waves are also used to grind small stones formed in the kidneys. These grinded grains are flushed with urine.

Question 3.
State some important characteristics of wave motion.
Answer:
Characteristics of wave motion are as follows:

1. It is the disturbance which travels forward through the medium and not the particles of the medium. The particles of the medium merely vibrate about their mean positions.
2. Each particle receives vibrations a little later than its preceding particle.
3. The velocity with which wave travels is different from the velocity of the particles with which they vibrate about their mean positions.
4. The wave velocity remains constant in a given medium while the particle velocity changes continuously during its vibration about the mean position.

Question 4.
How can a longitudinal wave be represented graphically?
Answer:
Graphical representation of a longitudinal wave:

Sound propagates as density or pressure variations as shown in (a), (b) and (c).

1. When a longitudinal wave passes through a medium, the particles of the medium come closer together and move away from one another alternately. Thus, alternate regions of increased and decreased density are created. These regions are called compressions and rarefactions respectively.
2. The figures (a) and (b) represent the density and pressure variations, respectively, as the sound wave propagates through a medium.
   Figure (c) represents the variations of density and pressure graphically.
3. The variation of density increases or decreases as the pressure of the medium at a given time increases or decreases with distance, above and below the average value of density and pressure.
4. The distance between two successive compressions (C) or two successive rarefactions (R) is called wavelength. It is usually represented by λ (lambda).

Question 5.
Explain the formation of waves with the help of an example.
Answer:
A wave is a pattern of disturbance which travels through a medium due to repeated vibrations of the particles of the medium, the disturbance being handed over from one particle to the next. The motion of the disturbance is called wave motion. If we drop a pebble into a pond of still water, a circular pattern of alternate crests and troughs spreads out from the point where the pebble strikes the water surface. The kinetic energy of the pebble makes the particles which come in contact with it oscillate.

These particles, in turn, transfer energy to the particles of next layer which begin to oscillate. Energy is further transferred to the particles of the next layer which also begin to oscillate and so on. In this way, energy is carried by the waves from one part to another. Further, if we throw pieces of paper or a cork on the water surface, it will oscillate up and down about its mean position and will not move forward with the wave. This shows that it is the disturbance of the wave which travels forward and not the particles of the medium.

Question 6.
A ship sends out ultrasound that returns from the seabed and is detected after 4 s. If the speed of ultrasound through seawater is 1550 m/s, what is the distance of the seabed from the ship?
Answer:
Time between transmission and detection, t = 4s
Speed of ultrasound in sea water,
v = 1550 m/s
Distance travelled by the ultrasound
= 2 × depth of the sea = 2d
where d is the depth of the sea.
2d = Speed of sound × time = 1550 m/s × 4s = 6200m
d =\(\frac{6200}{2}\) m = 3100 m = 3.1 km.
Thus, the distance of the seabed from the ship is 3100 m or 3.1 km.

Analysing & Evaluating Questions

Question 7.
A sound were travelling in a medium is represented as shown in the figure

(a) Which letter represents the amplitude of the sound wave?
(b) Which letter represents the wavelength of wave?
(c) What is the frequency of the source of sound if the vibrating source of sound makes 360 oscillations in 2 minutes?
Answer:
In the figure,
(a) The amplitude is represented by X.
(b) The wavelength is represented by Y.
(c) Frequency
= \(\frac{No. of oscillations }{ Time in sec onds}\) = \(\frac{360}{2 \mathrm{~min}}\)
= \(\frac{360}{2 \times 60 \mathrm{~s}}\) = 3s^-1 = Hz

Activity-1

• Take a tuning fork and set it vibrating by striking its prong on a rubber pad. Bring it near your ear and observe.
• Touch one of the prongs of the vibrating tuning fork with your finger and see what happens.
• Take a table tennis ball or a small plastic ball Now,Take a big needle and a thread, put a knot at one end of the thread, and then with the help of the needle, pass the thread through the ball. Suspend the ball from a support. Now, touch the ball gently with the prong of a vibrating tuning fork. Observe what happens.
  

Observations

• A sound is heard on bringing the vibrating fork near the ear.
• If we touch the ball with a turning fork set into vibration, the ball gets displaced from its mean position and starts oscillating.

Activity 2

• Fill water in a beaker or a glass up to the brim. Gently touch the water surface with one of the prongs of the vibrating tuning fork, as shown in the figure.
• Next, dip the prongs of the vibrating tuning fork in water, as shown in the figure.
• Observe what happens in both the cases.
  

Observations
In both the cases, sound will be produced by the turning fork which produces ripples in water. But in case (1), ripples are produced which will move up and down and in case (2), ripples are produced which will move sideways.

Activity 3

• Take a spring. Ask your friend to hold one of its end. You hold the other end. Now stretch the slinky as shown in the figure. Then give it a sharp push towards your friend and observe.
• Move your hand pushing and pulling the slinky alternatively and observe again.
  

Observations

• When we give a small jerk, a hump is produced and this travels forward. It represents a transverse wave.
• When we give a sharp push, a continuous disturbance is produced. This disturbance starts moving in the forward and backward direction parallel to the direction of propagation of the disturbance. It represents a longitudinal wave.
• If you mark a dot on the slinky, you will observe that the dot on the slinky will move back and forth parallel to the direction of the propagation of the disturbance.

Activity 4

• Take two identical pipes, as shown in the figure. You can make pipes using a chart paper. The length of the pipes should be sufficiently long as shown.
• Arrange them on a table near a wall.
• Keep a clock near the open end of one of the pipes and try to hear the sound of the clock through the other pipe.
• Adjust the position of the pipes, so that you can hear the best sound of the clock.
• Now, measure the angles of incidence and reflection and see the relationship between the angles.
• Lift the pipe on the right, vertically to a small height and observe what happens.
  

Observations

• Reflection of sound is similar to the reflection of light, i.e., angle of incidence = angle of reflection.
• If we lift the pipe vertically to a small height, we will not be able to hear the sound through the other end of the pipe because the incident sound wave, the reflected sound wave and the normal, all he in the same plane.

Value Based Questions

Question 1.
Sahil noticed that his pet dog was frightened and trying to hide in a safe place in his house when some crackers were burst in the neighbourhood. He realised the problem and he decided not to burst crackers during diwali or for any other celebrations.
1. What must be the range of sound of crackers?
2. Name two diseases that can be caused due to noise pollution.
3. Name the values of Sahil reflected in the above act.
Answer:

1. The range of crackers sound must be between 20 Hz and 20 kHz.
2. Two diseases that can occur due to noise pollution are heart attack and high blood pressure.
3. Sahil reflects the value of respect and sensitivity for animals and caring for animals.

Question 2.
It is not advisable to construct houses near airports. Inspite of that, many new apartments are constructed near airports. Rahul files RTI and also complains to the municipal office about the same?
1. Why should we not reside near airport?
2. Name two other places where there is noise pollution.
3. What value of Rahul is reflected in this act?
Answer:

1. The landing and taking off of the airplanes cause a lot of noise pollution which may lead to deafness, high blood pressure, and other health problems.
2. The other two places where there is noise pollution are heavy traffic routes and railway stations or lines.
3. Rahul shows the values of a responsible citizen and shows awareness.

JAC Class 9 Science Important Questions

Jharkhand Board JAC Class 10 Maths Solutions Chapter 4 Quadratic Equations Ex 4.2 Textbook Exercise Questions and Answers.

JAC Board Class 10 Maths Solutions Chapter 4 Quadratic Equations Exercise 4.2

Question 1.
Find the roots of the following quadratic equations by factorisation:
1. x² – 3x – 10 = 0
2. 2x² + x – 6 = 0
3. \(\sqrt{2}\)x² + 7x + 5\(\sqrt{2}\) = 0
4. 2x² – x + \(\frac{1}{8}\) = 0
5. 100x² – 20x + 1 = 0
Solution:
1. x² – 3x – 10 = 0
∴ x² – 5x + 2x – 10 = 0
∴ x(x – 5) + 2(x – 5) = 0
∴ (x – 5)(x + 2) = 0
Hence, x – 5 = 0 or x + 2 = 0
∴ x = 5 or x = -2
Thus, the roots of the given equation are 5 and -2.
Verification:
For x = 5,
LHS = (5)² – 3(5) – 10
= 25 – 15 – 10
= 0
= RHS
For x = -2,
LHS = (2)² – 3(-2) – 10
= 4 + 6 – 10
= 0
= RHS
Hence, both the roots are verified.
Note that verification is not a part of the solution. It is meant only for your confirmation of receiving correct solution.

2. 2x² + x – 6 = 0
∴ 2x² + 4x – 3x – 6 = 0
∴ 2x (x + 2) – 3(x + 2) = 0
∴ (x + 2) (2x – 3) = 0
∴ x + 2 = 0 or 2x – 3 = 0
∴ x = -2 or x = \(\frac{3}{2}\)
Thus, the roots of the given equation are -2 and \(\frac{3}{2}\)

3. \(\sqrt{2}\)x² + 7x + 5\(\sqrt{2}\) = 0
∴ \(\sqrt{2}\)x² + 2x + 5x + 5\(\sqrt{2}\) = 0
∴ \(\sqrt{2}\)x(x + \(\sqrt{2}\)) + 5(x + \(\sqrt{2}\)) = 0
∴ (x + \(\sqrt{2}\))(\(\sqrt{2}\)x + 5) = 0
∴ x + \(\sqrt{2}\) = 0 or \(\sqrt{2}\)x + 5 = 0
∴ x = –\(\sqrt{2}\) or x = \(-\frac{5}{\sqrt{2}}\)
Thus, the roots of the given equation are –\(\sqrt{2}\) and \(-\frac{5}{\sqrt{2}}\)

4. 2x² – x + \(\frac{1}{8}\) = 0
∴ 16x² – 8x + 1 = 0 (Multiplying by 8)
∴ 16x² – 4x – 4x + 1 = 0
∴ 4x(4x – 1) -1 (4x – 1) = 0
∴ (4x – 1) (4x – 1) = 0
∴ 4x – 1 = 0 or 4x – 1 = 0
∴ x = \(\frac{1}{4}\) or x = \(\frac{1}{4}\)
Thus, the repeated roots of the given equation are \(\frac{1}{4}\) and \(\frac{1}{4}\)

5. 100x² – 20x + 1 = 0
100x² – 10x – 10x + 1 = 0
10x(10x – 1) -1 (10x – 1) = 0
(10x – 1)(10x – 1) = 0
10x – 1 = 0 or 10x – 1 = 0
x = \(\frac{1}{10}\) or x = \(\frac{1}{10}\)
Thus, the repeated roots of the given equation are \(\frac{1}{10}\) and \(\frac{1}{10}\).

Question 2.
Solve the problems given in Textual Examples:
1. John and Jivanti together have 45 marbles. Both of them lost 5 marbles each, and the product of the number of marbles they now have is 124. Find out how many marbles they had to start with.
2. A cottage industry produces a certain number of toys in a day. The cost of production of each toy (in rupees) was found to be 55 minus the number of toys produced in a day. On a particular day, the total cost of production was ₹ 750. Find out the number of toys. produced on that day.
Solution:
1. Let the number of marbles that John had be x.
Then, the number of marbles that Jivanti had is (45 – x).
After losing 5 marbles, the number of marbles left with John = x – 5.
After losing 5 marbles, the number of marbles left with Jivanti = (45 – x) – 5 = 40 – x.
Therefore, the product of marbles with them is (x – 5) (40 – x), which is given to be 124.
Hence, we get the following equation:
(x – 5)(40 – x) = 124.
∴ 40x – x² – 200 + 5x = 124
∴ -x² + 45x – 324 = 0
∴ x² – 45x + 324 = 0
∴ x² – 36x – 9x + 324 = 0
∴ x(x – 36) – 9(x – 36) = 0
∴ (x – 36)(x – 9) = 0
∴ x – 36 = 0 or x – 9 = 0
∴ x = 36 or x = 9
Here, both the answers are admissible.
∴ 45 – x = 45 – 36 = 9 or
45 – x = 45 – 9 = 36
Thus, the number of marbles with John and Jivanti to start with are 36 and 9 respectively or 9 and 36 respectively.

2. Let the number of toys produced on that day be x.
Therefore, the cost of production (in rupees) of each toy on that day = 55 – x.
So, the total cost of production (in rupees) on that day = x (55 – x).
Hence, x(55 – x) = 750
∴ 55x – x² – 750 = 0
∴ x² – 55x + 750 = 0
∴ x² – 30x – 25x + 750 = 0
∴ x(x – 30) – 25(x – 30) = 0
∴ (x – 30)(x – 25) = 0
∴ x – 30 = 0 or x – 25 = 0
∴ x = 30 or x = 25
Here, both the answers are admissible.
Hence, the number of toys produced on that day is 30 or 25.

Question 3.
Find two numbers whose sum is 27 and product is 182.
Solution:
Let the first of the two numbers whose sum is 27 be x.
Then, the second number is 27 – x and the product of those two numbers is x (27 – x).
Their product is given to be 182.
∴ x (27 – x) = 182
∴ 27x – x² – 182 = 0
∴ x² – 27x + 182 = 0
∴ x² – 14x – 13x + 182 = 0
∴ x(x – 14) – 13(x – 14) = 0
∴ (x – 14)(x – 13) = 0
∴ x – 14 = 0 or x – 13 = 0
∴ x = 14 or x = 13
Here, both the answers are admissible.
Hence, if x = 14, it gives that the first number = x = 14 and the second number = 27 – x = 27 – 14 = 13.
And if x = 13, it gives that the first number = x = 13 and the second number = 27 – x = 27 – 13 = 14.
Thus, in either case, the required numbers are 13 and 14.

Question 4.
Find two consecutive positive integers, sum of whose squares is 365.
Solution:
Let two consecutive positive integers be x and x + 1.
Then, the sum of their squares = (x)² + (x + 1)²
= x² + x² + 2x + 1
= 2x² + 2x + 1
This sum is given to be 365.
∴ 2x² + 2x + 1 = 365
∴ 2x² + 2x – 364 = 0
∴ x² + x – 182 = 0
∴ x² + 14x – 13x – 182 = 0
∴ x(x + 14) – 13(x + 14) = 0
∴ (x + 14)( x- 13) = 0
∴ x + 14 = 0 or x – 13 = 0
∴ x = -14 or x = 13
Since x is a positive integer, x = -14 is inadmissible.
∴ x = 13 and x + 1 = 13 + 1 = 14
Thus, the required consecutive positive integers are 13 and 14.

Question 5.
The altitude of a right triangle is 7 cm less than its base. If the hypotenuse is 13 cm, find the other two sides.
Solution:
Let the base of the right triangle be x cm.
Then, its altitude is (x – 7) cm.
The hypotenuse of the right triangle is given to be 13 cm.
Now, by Pythagoras theorem.
(Base)² + (Altitude)² = (Hypotenuse)²
∴ (x)² + (x – 7)² = (13)²
∴ x² + x² – 14x + 49 = 169
∴ 2x² – 14x – 120 = 0
∴ x² – 7x – 60 = 0
∴ x² – 12x + 5x – 60 = 0
∴ x(x – 12) + 5(x – 12) = 0
∴ (x – 12)(x + 5) = 0
∴ x – 12 = 0 or x + 5 = 0
∴ x = 12 or x = -5
As the base of a triangle cannot be negative. x = -5 is inadmissible.
Hence, x = 12.
Then, the base of the triangle = x = 12 cm and the altitude of the triangle = x – 7 = 12 – 7
= 5 cm.
Thus, the base and the altitude of the given triangle are 12 cm and 5 cm respectively.

Question 6.
A cottage industry produces a certain number of pottery articles in a day. It was observed on a particular day that the cost of production of each article (in rupees) was 3 more than twice the number of articles produced on that day. If the total cost of production on that day was 90. find the number of articles produced and the cost of each article.
Solution:
Let the number of pottery articles produced on that day be x.
Then, according to the given, the cost of production (in rupees) of each article = 2x + 3.
Hence, total cost of production (in rupees) on that day = x(2x + 3) = 2x² + 3x.
This total cost of production is given to be ₹ 90.
∴ 2x² + 3x = 90
∴ 2x² + 3x – 90 = 0
∴ 2x² – 12x + 15x – 90 = 0
∴ 2x(x – 6) + 15(x – 6) = 0
∴ (x – 6) (2x + 15) = 0
∴ x – 6 = 0 or 2x + 15 = 0
∴ x = 6 or x = –\(\frac{15}{2}\)
Here, x = –\(\frac{15}{2}\) is inadmissible as x represents the number of articles produced.
Hence, x = 6 and 2x + 3 = 2(6) + 3 = 15.
Thus, the number of pottery articles produced on that day is 6 and the cost of production of each article is ₹ 15.

Jharkhand Board JAC Class 10 Maths Solutions Chapter 5 Arithmetic Progressions Ex 5.4 Textbook Exercise Questions and Answers.

JAC Board Class 10 Maths Solutions Chapter 5 Arithmetic Progressions Exercise 5.4

Question 1.
Which term of the AP 121, 117, 113, …. is its first negative term?
[Hint: Find n for a_n < 0]
Solution :
For the given AP 121, 117, 113, … a = 121 and d= 117 – 121 = – 4.
Let n^th term of the AP be its first negative term.
∴ a_n < 0
∴ a + (n – 1) d < 0
∴ 121 + (n – 1)(- 4) < 0
∴ 121 < 4 (n – 1) ∴ n > \(\frac{125}{4}\)
∴ n > 31\(\frac{1}{4}\)
Now, n being the number of a term is a positive integer and the smallest positive integer satisfying n > 31\(\frac{1}{4}\) is 32.
Hence, the 32nd term of the given AP is its first negative term.

Question 2.
The sum of the third and the seventh terms of an AP is 6 and their product is 8. Find the sum of first sixteen terms of the AP.
Solution :
For the given AP, let the first term be a and the common difference be d.
a_n = a + (n – 1) d
∴ a₃ = a + 2d and a₇ = a + 6d
According to given information,
a₃ + a₇ = 6
∴ (a + 2d) + (a + 6d) = 6
∴ 2a + 8d = 6
∴ a + 4d = 3
∴ a = 3 – 4d …………….(1)
Again, the product of a₃ and a₇ is 8.
∴ (a + 2d) (a + 6d) = 8
∴ (3 – 4d + 2d) (3 – 4d + 6d) = 8 [by (1)]
∴ (3 – 2d) (3 + 2d) = 8
∴ 9 – 4d² = 8
∴ 1 = 4d²
∴ d² = \(\frac{1}{4}\)
∴ d = \(\frac{1}{2}\) or d = – \(\frac{1}{2}\)

Thus, the required sum of first sixteen terms is 76 or 20.

Question 3.
A ladder has rungs 25 cm apart. (see the given figure). The rungs decrease uniformly in length from 45 cm at the bottom to 25 cm at the top. If the top and the bottom rungs are 2\(\frac{1}{2}\)m apart, what is the length of the wood required for the rungs?
Solution :

The distance between the top rung and the bottom rung = 2\(\frac{1}{2}\)m = 250 cm.
The distance between two successive rungs = 25 cm.
∴ Total number of rungs = \(\frac{250}{25}\) + 1 = 11
Including the top rung as well as the bottom rung
The length of the first (bottom) rung = 45 cm.
The length of the 11th rung at top = 25 cm.
The length of rung decreases uniformly.
Hence, the lengths (in cm) of rungs form an AP in which the first term = 45 and 11th term = 25.
a_n = a+ (n – 1)d
∴ a₁₁ = a + 10 d
∴ 25 = 45 + 10 d
∴ – 20 = 10 d
∴ d = – 2
Thus, the length of rung uniformly decreases by 2 cm as we move from bottom to top.
Thus, the lengths (in cm) of rungs form a finite AP 45, 43, 41, ……….with 11 terms.
Then, sum of all the eleven terms will give the total length of the wood required for the rungs.
S_n = \(\frac{n}{2}\)(a + 1)
∴ S₁₁ = \(\frac{11}{2}\)(45 + 25)
∴ S₁₁ = \(\frac{11}{2}\) × 70
∴ S₁₁ = 385
Thus, the total length of the wood required for the rungs is 385 cm.

Question 4.
The houses of a row are numbered consecutively from 1 to 49. Show that there is a value of x such that the sum of the numbers of the houses preceding the house numbered x is equal to the sum of the numbers of the houses following it. Find this value of x.
[Hint: S_x-1 = S₄₉ – S_x]
Solution :
We know the sum of first n positive integers n(n+1) is given by S_n = \(\frac{n(n+1)}{2}\)
According to data, 1 + 2 + 3 + ……… + (x – 1) = (x + 1) + (x + 2) + ……….. + 49
∴ \(\frac{(x-1) \cdot x}{2}\) = (1 + 2 + 3 + … + 49) – (1 + 2 + 3 + … + x)
[Adding and subtracting (1 + 2 + 3 + … + x)}
∴ \(\frac{(x-1)(x)}{2}=\frac{49 \times 50}{2}-\frac{x(x+1)}{2}\)
∴ x(x – 1) + x(x + 1) = 49 × 50
∴ x² – x + x² + x = 49 × 50
∴ 2x² = 49 × 50
∴ x² = \(\frac{49 \times 50}{2}\)
∴ x² = 49 × 25
∴ x = 7 × 5
∴ x = 35
Thus, the value of x is 35.

Question 5.
A small terrace at a football ground comprises of 15 steps each of which is 50 m long and built of solid concrete. Each step has a rise of \(\frac{1}{4}\)m and a tread of \(\frac{1}{2}\)m (see the given figure). Calculate the total volume of concrete required to build the terrace.
[Hint: Volume of concrete required to build the first step = \(\frac{1}{4}\) × \(\frac{1}{2}\) × 50 m³]
Solution :

Volume of concrete required to build the first step = 50 × \(\frac{1}{2}\) × \(\frac{1}{4}\)m³ = \(\frac{25}{4}\)m³
Volume of concrete required to build the second step = 50 × \(\frac{1}{2}\) × (\(\frac{1}{4}\) + \(\frac{1}{4}\))m³ = \(\frac{25}{2}\)m³
Volume of concrete required to build the third step = 50 × \(\frac{1}{2}\) × (\(\frac{1}{4}\) + \(\frac{1}{4}\) + \(\frac{1}{4}\))m³ = = \(\frac{75}{4}\)m³ and so on up to 15 steps.
Thus, the volumes (in m³) of concrete required to build those 15 steps form the finite AP \(\frac{25}{4}\), \(\frac{25}{2}\), \(\frac{75}{4}\) …with 15 terms.
The sum of all the fifteen terms will give the quantity of total concrete required.
Here, a = \(\frac{25}{4}\), d = \(\frac{25}{2}-\frac{25}{4}=\frac{25}{4}\) and n = 15.
S_n = \(\frac{n}{2}\)[(2a + (n – 1) d]
∴ S₁₅ = \(\frac{15}{2}\)[\(\frac{25}{2}\) +(15 – 1)\(\frac{25}{4}\)]
∴ S₁₅ = \(\frac{15}{2}\) [latex]\frac{25}{2}+\frac{175}{2}[/latex]
∴ S₁₅ = \(\frac{15}{2} \times \frac{200}{2}\)
∴ S₁₅ = 15 × 50
∴ S₁₅ = 750
Thus, 750 m³ of concrete is required to build the terrace.

JAC Board Class 9th Social Science Solutions Civics Chapter 3 Electoral Politics

JAC Class 9th Civics Electoral Politics InText Questions and Answers 

Questions of Unni & Munni (Page No. 35)

Question 1.
Do most leaders fulfil their election promises?
Answer:
During elections, most of the leaders make many big promises to the people/voters to win their support and vote. However, after the elections, most of the political leaders forget their promises and do not fulfil their election promises.

Check Your Progress (Page No. 36)

Question 2.
Jagdeep and Navpreet read this story and drew the following conclusions. Can you say which of these are right or wrong (or if the information given in the story is inadequate to call them right or wrong):
1. Elections can lead to changes in the policy of the government.
2. The Governor invited Devi Lai to become the Chief Minister because he was impressed with his speeches.
3. People are unhappy with every ruling party and vote against it in the next election.
4. The party that wins the election forms the government.
5. This election led to a lot of economic development in Haryana.
6. The congress Chief Minister need not have resigned after his party lost elections.
Answer:

1. Right,
2. Wrong,
3. Inadequate information,
4. Right,
5. Inadequate information,
6. Wrong.

Activity (Page No. 36)

Question 1.
Do you know when the last Assembly election was held in your state? Which other elections have taken place in your locality in the last five years? Write down the level of elections (National, Assembly, Panchayat etc.), when were they held and the name and designation (MP, MLA, etc.) of the persons who got elected from your area.
Answer:
Do it yourself.

Questions of Unni & Munni (Page No. 36, 37)

Question 1.
We have seen why democracies need to have elections. But why do rulers in non- democratic countries need to hold elections?
Answer:
Rulers in non-democratic countries hold elections because they need to show that their government and position has been achieved legally and according to the constitutional provisions.
Secondly, they want to show the world that they are not unpopular and they have the support of the people of the country which will improve their image in the sight of the world.

Question 2.
Ah! So, elections are like exams where politicians and parties know if they have passed or failed. But who are the examiners?
Answer:
In this case, the examiners are the voters, who give them marks in the form of votes.

Read the Cartoon (Page No. 38)

Question 1.
Read these two cartoons carefully. Write the message of each of them in your own words.
Have a discussion in class on which of the two is closer to the reality in your own locality. Draw a cartoon to depict what elections do to the relationship between voters and political leaders.
Answer:

1. The first cartoon depicts that knowledge, planning, promises of a leader is useless if he has not achieved the essential votes.
2. The second cartoon depicts that leaders made a lot of promises during the election campaign and achieved power. But voters are always in the hope that all promises have to be fulfilled by those leades.
   • Student discuss yourself in your class.
   • Draw the cartoon yourself.

Map based Question (Page No. 39)

Question 1.
Why is the boundary of the Gulbarga Lok Sabha constituency not the same as the district boundary of Gulbarga?
Answer:
The boundary of the Gulbarga Lok Sabha constituency is not the same as the district boundary of Gulbcrga because:

1. Whole Karnataka State is divided into Lok Sabha constituencies according to its population
2. The population of Gulbarga district is more than that allotted for each Lok Sabha constituency in the state.

Question 2.
Draw a similar map for your own Lok Sabha constituency.
Answer:
Students draw it yourself.

Question 3.
How many Assembly constituencies are there in the Gulbarga Lok Sabha constituency?
Answer:
There are 8 Assembly constituencies in the Gulbarga Lok Sabha constituency.

Question 4.
Is it the same in your own Lok Sabha constituency?
Answer:
Students do it yourself.

Questions of Unni & Munni (Page No. 40)

Question 1.
Like in Panchayats, should we not have at least one-third seats in the parliament and assemblies reserved for women?
Answer:
Since women make half of the population of our society, that’s why we must have at least one-third seats in the parliament and assemblies reserved for women.

Map based Question (Page No. 41)

Question 1.
See the map above (see map on textbook page no. 41) and answer the following questions.
1. What is the number of Lok Sabha constituencies in your state and the neighbouring two states?
Answer:
In Rajasthan, the number of Lok Sabha constituencies is 25. In its neighbouring two states, i.e., Gujarat and Uttar Pradesh, the number of constituencies are 26 and 80 respectively.

2. Which states have more than 30 Lok Sabha constituencies?
Answer:
Bihar (40), Maharashtra (48), Uttar Pradesh (80), West Bengal (42), and Tamil Nadu (39).

3. Why do some states have such a large number of constituencies?
Answer:
The number of constituencies is determined by the area and size of population of a state.

4. Why are some constituencies small in area while others are very big?
Answer:
The size of a constituency depends on its voters. An effort is made to give equal representation to whole of the population.

5. Are the constituencies reserved for the SCs and STs evenly spread all over the entire country or are there more in some areas?
Answer:
No, the constituencies reserved for the SCs and STs are not evenly spread all over the entire country. They are more in those areas where there is increased concentration of SCs, STs population.

Questions of Unni & Munni (Page No. 42)

Question 1.
Why are the candidates required to give a detailed statement of their property?
Answer:
Candidates are required to give a detailed statement of their property at the time of election because the Election Commission makes efforts to control the misuse of money power in elections. The candidate has to give information about his movable and immovable property, loan from financial institutions, tax status and income. With this information, the voters will be able to know more about the candidates and make their correct choice.

Check Your Progress (Page No. 66)

Question 1.
Match the following features of our electoral system with the principles they reflect.

Principles	Features of election system
Universal Adult Franchise	Each constituency has roughly the same population
Representation of weaker sections	Everyone who is 18 years of age or older, has a right to vote
Open political competition	Anyone can form a party or contest elections
One vote one value	Reservation of seats for the SCs and the STs

Answer:

Principles	Features of election system
Universal Adult Franchise	Everyone who is 18 years of age or older, has a right to vote
Representation of weaker sections	Reservation of seats for the SCs and the STs
Open political competition	Each constituency has roughly the same population
One vote one value	Anyone can form a party or contest elections

Activity (Page No. 44)

Question 1.
What was the election campaign like in your constituency in the last Lok Sabha elections? Prepare a list of what the candidates and parties said and did.
Answer:
Do it yourself.

Questions of Unni & Munni (Page No. 46)

Question 1.
Why are party agents present in the polling booth and the counting centre?
Answer:
Party agents are present in the polling booth and the counting centre because:

1. They ensure that the voting takes place in a fair way.
2. They ensure in the counting centre that the counting is done properly without any unfair means.

Check Your Progress (Page No. 46)

Question 1.
Identify the fair and the unfair electoral practices among the following:
1. A minister flags off a new train in his constituency a week before polling day.
2. A candidate promises that she will get a new train for her constituency if she is elected.
3. Supporters of a candidate take the voters to a temple and make them take an oath that they will vote for him.
4. The supporters of a candidate distribute blankets in slums in return for a promise for vote.
Answer:

1. Unfair electoral practice,
2. Fair electoral practice,
3. Unfair electoral practice,
4. Unfair electoral practice.

Questions of Unni & Munni (Page No. 47)

Question 1.
Why does the Election Commission have so much powers ? Is this good for democracy?
Answer:

1. The Election Commission have so much powers to conduct the free and fair elections and to check the unfair practices during the election.
2. Yes, this is good for democracy.

Check Your Progress (Page No. 48)

Question 1.
Read these headlines carefully and identify which powers are used by the Election Commission in each instance to ensure free and fair elections.
1. EC issues notification constituting 14th Lok Sabha.
Answer:
Election Commission takes decisions on every aspect of conduct and control of elections, from the announcement of elections to be declaration of results.

2. EC tightens norms for poll expenses. EC to visit Gujarat again, review poll arrangements.
Answer:
The Election Commission has fixed the amount to be spent by the candidates for each parliamentary and assembly seat. Because some political parties or candidates who have more resources can take advantage of it, the Commission has exercised its authority to conduct fair elections.

3. EC to visit Gujarat again to review poll arrangements.
Answer:
The Election Commission made another visit to review the electoral system in Gujarat due to reports of the possibility of capturing and rigging the polling stations. The commission is exercising its power to conduct free and fair elections.

4. HC asks EC to bar ‘criminal’ netas.
Answer:
Election commission takes decisions on every aspect of conduct and control of elections.

5. EC Shoots down HM advice on poll reforms.
Answer:
The Election Commission is responsible for conducting free and fair elections. The final decisional in this regard is taken by it only. It is free not to accept any suggestion. Therefore it did not accept the election suggestion of the Home Ministry.

6. Photo I-cards not mandatory in Bihar polls.
Answer:
Election Commission takes decision on every aspect of elections and control of elections from the announcement of elections to the declaration of results. It also includes the powers relating to the identification of the voters.

7. EC accepts new Haryana DGP.
Answer:
The Haryana government has transferred the current DGP as per the Commission’s directive. The Commission has used its power to transfer or appoint an impartial office for a fair election here.

8. EC will seek power to censure political ads.
Answer:
At the time of elections, political parties resort to political advertisements to discredit each
other, so the Election Commission, while exercising its power to conduct free and fair elections, allowed only those advertisements which do not accuse others.

9. EC says no immediate plan to ban Exit Polls.
Answer:
Election Commission takes decisions on every aspect of conduct and control of elections, from the announcement of elections to the declaration of results. It also includes power regarding the control of the exit polls.

10. EC orders repoll in 398 more booths.
Answer:
Election Commission takes decisions on every aspect of conduct and control of elections from the announcement of elections and order to repoll to the declaration of results.

11. EC to keep closer eye on hidden poll costs.
Answer:
Election Commission implements election laws and the code of conduct and punishes any candidate or political party that violates it. Thus, every party or candidate can get a fair and equal chance to compete.

Activity (Page No. 49)

Question 1.
Ask the eligible voters in your family whether they voted in the last election to the Lok Sabha or to the state assembly. If they did not, ask them why did they not vote. If they did, ask them which party and candidate they voted for and why. Also ask them whether they had participated in any other election-related activity like attending an election meeting or rally etc.
Answer:
Do it yourself.

Read the Cartoon (Page No. 50 – 51)

Question 1.
The leader is coming out of a press conference: “What was need to say that we have distributed tickets only amongst suitable and winnable family relations ?” Do you think that family politics is confined to only a few states or parties?
Answer:
I think that family politics is confined to not only a few states or parties but it is spread all over India.

Question 2.
Titled ‘Electoral Campaigns’, this cartoon was drawn in the Latin American context. Does this apply to India and to other democracies in the world?
Answer:
Yes, this cartoon applies to India and to other democracies in the world also because each candidate is allowed to spend a definite amount of money on the election campaign.

Question 3.
Is this an accurate picture (Page No. 51) of what happens to the voter before and after elections? Must this always happen in a democracy? Can you think of examples when this did not happen?
Answer:

1. Yes, this is an accurate picture of what happens to the voter before and after elections.
2. No, this must not be always happen in a democracy.
3. No.

Check Your Progress (Page No. 51)

Question 1.
Here are some facts on Indian elections. Comment on each of these to say whether they reflect the strength or the weakness of our electoral system.
1. The Lok-Sabha has 12 percent women members.
Answer:
Reflects the weakness of our electoral system.

2. The Election Commission often refuses to accept the government’s advice about when the elections should be held.
Answer:
Reflects the strength of our electoral system.

3. The 16th Lok Sabha has more than 440 members whose assets are more than Rs. 1 crore.
Answer:
Reflects the weakness of our electoral system.

4. After losing an election the Chief Minister said: “I respect the people’s verdict.”
Answer:
Reflects the strength of our electoral system.

JAC Class 9th Civics Electoral Politics Textbook Questions and Answers 

Question 1.
Which of the following statements about the reasons for conducting elections are false?
(a) Elections enable people to judge the performance of the government.
(b) People select the representative of their choice in an election.
(c) Elections enable people to evaluate the performance of the judiciary.
(d) People can indicate which policies they prefer.
Answer:
(c) Elections enable people to evaluate the performance of the judiciary.

Question 2.
Which of these is not a good reason to say that Indian elections are democratic?
(a) India has the largest number of voters in the world.
(b) India’s Election Commission is very powerful.
(c) In India, everyone above the age of 18 has a right to vote.
(d) In India, the losing parties accept the electoral verdict.
Answer:
(a) India has the largest number of voters in the world.

Question 3.
Match the following:

It is necessary to keep the voters’ list up to date because	There is a fair representation of all sections of our society
Some constituencies are reserved for SCs and STs so that	Everyone has equal opportunity to elect their representative
Everyone has one and only one vote so that	All candidates must have a fair chance of competing in elections
Party in power is not allowed to use government vehicles because	Some people may have moved away from the area where they voted last

Answer:

(a) It is necessary to keep the voters’ list up to date because	4. Some people may have moved away from the area where they voted last
(b) Some constituencies are reserved for SCs and STs so that	1. There is a fair representation of all sections of our society
(c) Everyone has one and only one vote so that	2. Everyone has equal opportunity to elect their representative
(d) Party in power is not allowed to use government vehicles because	3. All candidates must have a fair chance of competing in elections

Question 4.
List all the different election related activities mentioned in the chapter and arrange them in a time sequence, beginning with the first activity and ending with the last. Some of these activities are given below: Releasing election manifestos; counting of votes; making of voters’ list; election campaign; declaration of election results; casting of votes; ordering of re-poll; announcing election schedule; filing nomination.
Answer:

1. Making of voter’ list;
2. Filing nomination;
3. Election campaign;
4. Ordering of re-poll;
5. Declaraton of election results;

Question 5.
Surekha is an officer in-charge of ensuring free and fair elections in an assembly constituency in a state. Describe what should she focus on for each of the following stages of election:
(a) Election campaign,
(b) Polling day,
(c) Counting day.
Answer:
(a) Election Campaign:
She should ensure that election campaign is totally according to the norms of Election Commission and ends before 48 hours of polling.

(b) Polling day: Polling day should be peaceful without any violence or fake polling or rigging.

(c) Counting day: Counting should be done in fair manner and only genuine candidate, who has actually won, should be declared so.

Question 6.
The table below gives the proportion of different communities among the candidates who won elections to the US Congress. Compare these to the proportion of these communities in the population of the US. Based on this, would you suggest a system of reservation in the US Congress? If yes, why and for which communities? If no, why not?

	Proportion of the Community (in per cent), in the
	House of representatives	Population of US
Blacks	8	13
Hispanics	5	13
Whites	86	70

Answer:
Based on the figures given in the table, it is clear that Blacks and hispanics have much less representation than their population in the US Congress. Some seats may be reserved for the blacks and the hispanics in the US Congress. In an open electoral competition, certain weaker sections may not stand a chance to get elected. They may not have the required resources, education and contacts to contest and win elections against others. Those who are influential and resourceful may prevent them from winning election.

Question 7.
Can we draw the following conclusions from the information given in this chapter ? Give two facts to support your position for each of these.
(a) Election Commission of India does not have enough powers to conduct free and fair elections in the country.
(b) There is a high level of popular participation in the elections in our country.
(c) It is very easy for the party in power to win an election.
(d) Many reforms are needed to make our elections completely free and fair.
Answer:
(a) No, this conclusion is not true.
(i) EC can prevent use and misuse of government machinery by party in power.
(ii) Government officers on election duty act under the order of the EC.

(b) Yes, this conclusion is true.
(i) All voters are free to vote.
(ii) Nobody can use force to prevent any voter from voting.

(c) No, this conclusion is not true.
(i) All parties have to follow the same code of conduct.
(ii) Party in power cannot use government machinery.

(d) Yes, this conclusion is true.
(i) Criminals are increasingly appearing as candidates.
(ii) The use of money power is becoming more obvious.

Question 8.
Chinappa was convicted for torturing his wife for dowry. Satbir was held guilty of practicing untouchability. The court did not allow either of them to contest elections. Does this decision go against the principles of democratic elections ?
Answer:
No, this decision does not go against the principles of democratic elections because they are criminals and criminals cannot contest elections.

Question 9.
Here are some reports of electoral malpractices from different parts of the world. Is there anything that these countries can learn from India to improve their elections? What would you suggest in each case?
(a) During an election in Nigeria, the officer in charge of counting votes deliberately increased the votes of one candidate and declared him elected. The court later found out that more than five lakh votes cast for one candidate were counted in favour of another.

(b) Just before elections in Fiji, a pamphlet was distributed warning voters that a vote for former Prime Minister, Mahendra Chaudhry, will lead to bloodshed. This was a threat to voters of Indian Origin.

(c) In the US, each state has its own method of voting, its own procedure of counting and its own authority for conducting elections. Authorities in the state of Florida took many controversial decisions that favoured Mr. Bush in the presidential elections in 2000. But no one could change those decisions.
Answer:
(a) Yes, Nigeria can learn from Indian vote counting system. Nigeria should adopt the method of counting like India’s election system. At the time of counting of votes, agents of all the candidates participating in the elections are present and the votes are counted in front of them. And if there is any doubt, the counting of votes can be done again. In addition to this, the government of Nigeria should also use Electronic Voting Machines (EVM) for voting.

(b) Yes, the people of Fiji can learn from the Indian electoral system. There should be such a powerful agency to deal with such threats, which can take immediate punitive action and voters can vote fairly. There should also be a provision that any party found to be involved in such activities will be debarred from contesting elections.

(c) The United States of America can learn from the Indian electoral system. India has a united system for conducting elections i.e., National Election Commission. Its rules and orders are followed equally throughout the country. This institution is independent and free from government influence. It can prohibit government decisions at the time of elections if they are not in the interest of free and fair elections.

Question 10.
Here are some reports of malpractices in Indian elections, identify what the problem in each case is. What should be done to correct the situation?
(a) Following the announcement of elections, the minister promised to provide financial aid to reopen the closed sugar mill.
(b) Opposition parties alleged that their statements and campaign was not given due attention in Doordarshan and All India Radio.
(c) An inquiry by the Election Commission showed that electoral rolls of a state contain name of 20 lakh fake voters.
(d) The hoodlums of a political party were moving with guns, physically preventing suporters of other political parties to meet the voters and attacking meeting of other parties.
Answer:
(a) The announcement made by the minister other the announcement of the election is a move affecting public opinion that could impede fair elections. This is an open violation of the code of conduct. For this, the Election Commission should issue a show cause notice to the minister, and if it not get the required response, it should declare his declaration invalid and take punitive action against him.

(b) This allegation of the opposition parties hinders the conduct of fair elections. This has not given equal opportunity to the opposition parties to reach out to the public. Therefore, voting may be affected. The Election Commission should get it investigated and if the complaint is found correct, then it should arrange for those parties to also communicate their view on Doordarshan and All India Radio.

(c) This way, there will be no free and fair election because all these voters can vote in favour of one party. This will affect the election results. The Election Commission should dismiss this voters’ list and issue an order to prepare the correct voters’ list. Alongwith this, orders should also be issued to punish the officials who made the wrong voters’ list.

(d) Criminalization of politics cannot lead to free and fair elections. People will not go to participate in elections for fear of criminals, thinking that they will win by illegal voting. The Election Commission should identify such people and related political party and take appropriate action against them. Proper security should be provided to all the candidates and the public should also be motivated to participate in the voting fearlessly.

Question 11.
Ramesh was not in class when this chapter was being taught. He came the next day and repeated what he had heard from his father. Can you tell Ramesh what is wrong with these statements?
(a) Women always vote the way men tell them to. So what is the point of giving them the right to vote?
(b) Party politics creates tension in society. Elections should be decided by consensus, not by competition.
(c) Only graduates should be allowed to stand as condidates for elections.
Answer:
(a) This statement is wrong. Women have an independent vote; they do exercise their vote on their own thinking.

(b) It is wrong. In a system of consensus, mighty and powerful will come to dominate and exploit poor and weaker sections of the society. Open elections creates a guarantee against such an exploitation.

(c) It is wrong. Educational qualifications do make a citizen more knowledgeable and alive towards the social and political situation, but the converse is not true. Every citizen, irrespective of his educational status, should be allowed his civil right to stand for elections.

JAC Class 9 Social Science Solutions

JAC Board Class 9th Science Important Questions Chapter 1 Matter in Our Surroundings

Multiple Choice Questions

Question 1.
Evaporation of a liquid occurs at
(a) boiling point
(b) a fixed temperature
(c) temperature lower than boiling point
(d) all temperatures
Answer:
(c) temperature lower than boiling point

Question 2.
Intermolecular force of attraction is maximum in
(a) Solids
(b) Liquids
(c) Gases
(d) Plasma particles
Answer:
(a) Solids

Question 3.
………… will not exhibit diffusion.
(a) Hydrogen and oxygen
(b) Oxygen and water
(c) Salt and sand
(d) Sugar crystal and water
Answer:
(c) Salt and sand

Question 4.
Which of the following substances is not a solid?
(a) Air
(b) Butter
(c) Sponge
(d) Rubber band
Answer:
(a) Air

Question 5.
Which one of the following properties is not a characteristic of liquids?
(a) Fluidity
(b) Definite shape
(c) Definite volume
(d) Compressibility
Answer:
(b) Definite shape

Question 6.
Fusion is the process in which
(a) liquid changes into gas
(b) solid changes into liquid
(c) solid changes into gas
(d) gas changes into solid
Answer:
(b) solid changes into liquid

Question 7.
The density of water is maximum at
(a) 0°C
(b) 100°C
(c) 4°C
(d) 273K
Answer:
(c) 4°C

Question 8.
Choose the correct statement from the following:
(a) Two gases cannot diffuse into each other.
(b) The volume of gas expands on heating.
(c) Conversion of a gas into solid is called condensation.
(d) Gases cannot diffuse in solids.
Answer:
(b) The volume of gas expands on heating.

Question 9.
Which among the following can exist in vapour state?
(a) Oxygen
(b) Hydrogen
(c) Carbon dioxide
(d) Water
Answer:
(d) Water

Question 10.
Cooking of rice at higher altitudes is difficult because
(a) water boils at temperature <100°C
(b) water boils at 100°C
(c) boiling point of water is constant
(d) none of the above
Answer:
(a) water boils at temperature <100°C

Question 11.
At normal pressure, the boiling point of water is
(a) 98°C
(b) 100°C
(c) 110°C
(d) 90°C
Answer:
(b) 100°C

Question 12.
Gases do not have
(a) high compressibility
(b) high fluidity
(c) high density
(d) volume
Answer:
(c) high density

Question 13.
Molecules of a liquid
(a) have very strong intermolecular forces
(b) cannot move randomly
(c) have definite shape
(d) have large intermolecular spaces
Answer:
(d) have large intermolecular spaces

Question 14.
………….. decreases the rate of evaporation.
(a) Surface area
(b) Humidity
(c) Temperature
(d) Wind
Answer:
(b) Humidity

Question 15.
…………… does not convert a liquid into vapours.
(a) Boiling
(b) Evaporation
(c) Heating
(d) Condensation
Answer:
(d) Condensation

Analysing & Evaluating Questions

Question 16.
Seema visited a Natural Gas Compressing Unit and found that the gas can be liquefied under specific conditions of temperature and pressure. While sharing her experience with friends, she got confused. Help her to identify the correct set of conditions for liquefaction of gases.
(a) Low temperature, low pressure
(b) High temperature, low pressure
(c) Low temperature, high pressure
(d) High temperature, high pressure
Answer:
(c) Low temperature, high pressure

Question 17.
Under which of the following conditions, the distance between the molecules of hydrogen gas would increase?
I. Increasing pressure on hydrogen contained in a closed container.
II. Some hydrogen gas leaking out of the container.
III. Increasing the volume of the container of hydrogen gas.
IV. Adding more hydrogen gas to the container without increasing the volume of the container.
(a) I and III
(b) I and IV
(c) II and III
(d) II and IV
Answer:
(c) II and III

Question 18.
A substance has a definite shape, fixed volume, distinct boundary and cannot be compressed. What is the physical state of this substance?
(a) Solid
(b) Liquid
(c) Gas
(d) Plasma
Answer:
(a) Solid

Assertion – Reason Questions

Directions: In the following questions, the Assertions and the Reasons have been put forward. Read the statements carefully and choose the correct alternative from the following:
(A) Both the assertion and the reason are correct and the reason is the correct explanation of the assertion.
(B) The assertion and the reason are correct but the reason is not the correct explanation of the assertion.
(C) The assertion is true but the reason is false.
(D) Both statements are false.
1. Assertion: Gases diffuse faster than liquids.
Reason: Particles of gases have higher kinetic energy than those of liquids.
Answer:
(A) Both the assertion and the reason are correct and the reason is the correct explanation of the assertion.

2. Assertion: Solids have negligible compressibility.
Reason: In solids, the intermolecular force of attraction is very strong.
Answer:
(B) The assertion and the reason are correct but the reason is not the correct explanation of the assertion.

3. Assertion: Evaporation always takes place at the surface of a liquid.
Reason: Molecules at the surface of liquids have higher temperature.
Answer:
(C) The assertion is true but the reason is false.

4. Assertion: On heating or cooling, the physical state of a substance gets changed.
Reason: State of matter can be changed only by changing its temperature.
Answer:
(C) The assertion is true but the reason is false.

5. Assertion: Solids generally lack the property of diffusion.
Reason: In solids, intermolecular space is negligible.
Answer:
(A) Both the assertion and the reason are correct and the reason is the correct explanation of the assertion.

Very Short Answer Type Questions

Question 1.
What is matter?
Answer:
Anything that has mass and occupies space is called matter. For examples, rocks, plants, paper. chalk, water, food. etc.

Question 2.
In what ways are all substances around us alike?
Answer:
All the substances are matter, i.e., they all have mass and occupy space. Therefore, they are all alike.

Question 3.
Why is the rate of diffusion faster in gases?
Answer:
Because the intermolecular force of attraction is minimum in gases.

Question 4.
Why are light and sound not considered as matter?
Answer:
Light and sound are not considered as matter because they have no mass and they do not occupy space.

Question 5.
Name the three states of matter.
Answer:
Solid, liquid and gas are the three states of matter.

Question 6.
Ice and water are basically the same substance. Mention two differences in their properties.
Answer:

1. Ice: It has fixed volume and definite shape. It can be stored without a container.
2. Water: It is a liquid and has no definite shape. It cannot be stored without a container.

Question 7.
Classify the following materials according to the state in which they exist around us. Steel, blood, air, oil, rubber, honey, carbon dioxide, kerosene, LPG, CNG, nitrogen, oxygen
Answer:

• Solid: Steel, rubber.
• Liquid: Blood, oil, honey, kerosene, LPG.
• Gas: Air, carbon dioxide. CNG. nitrogen. oxygen.

Question 8.
Defineeflne boiling point.
Answer:
Boiling point ofa liquid is the temperature at which its pressure becomes equal to that of the atmospheric pressure and it starts vaporising into gaseous state.

Question 9.
Define melting point.
Answer:
The temperature at which a solid starts melting to become a liquid at atmospheric pressure is known as its melting point.

Question 10.
Latent heat of vaporisation of two liquids A and B is 100 kg and 150 kg respectively. What does It indicate?
Answer:
Latent heat of vaporisation depends on the nature of the liquid. Intermolecular

Question 11.
Which of the following shows the phenomenon of sublimation? Solid water, solid carbon dioxide, solid alcohol, solid oxygen
Answer:
Solid carbon dioxide.

Question 12.
How does spreading of wet clothes quicken their drying? Explain.
Answer:
Spreading of wet clothes increases surface area and so evaporation becomes faster. Thus, drying of wet clothes becomes faster by spreading them.

Question 13.
How does temperature affect the rate of evaporation?
Answer:
With increase of temperature, more number of particles get enough kinetic energy to change into the vapour state. Hence, rate of evaporation increases with increase in temperature.

Question 14.
Which will have more impact on kinetic energy: doubling mass or velocity?
Answer:
Doubling of velocity will increase kinetic energy four times. (KE = \(\frac{1}{2}\) mv²)

Question 15.
What is dry ice?
Answer:
Solid carbon dioxide obtained by cooling and applying pressure on carbon dioxide gas is called dry ice. it does not melt but directly transforms into vapour state, so it is called dry ice.

Question 16.
What is humidity?
Answer:
The air which holds water vapour is called humid air and the amount of water vapour present in the air is called humidity.

Question 17.
Define atmospheric pressure.
Answer:
The pressure exerted by the earth’s atmosphere at any given point is known as atmospheric pressure. The atmospheric pressure at sea level is atmosphere and is taken as the normal atmospheric pressure.

Analysing & Evaluating Questions

Question 18.
Alka was making tea in a kettle. Suddenly, she felt intense heat from the puff of steam gushing out of the spout of the kettle. She wondered whether the temperature of the steam was higher than that of the water boiling in the kettle. Comment.
Answer:
Temperature of steam is the same as that of boiling water. Intense heat of the steam is due to its high latent heat.

Question 19.
The energy changes in the following transformation are as follows:

In which of the above, the intennolecu lar forces are stronger?
Answer:
The intermolecular forces are stronger in water at 100°C.

Question 20.

You are given the following substances with their melting and boiling points.

Substance	Melting Boiling point (°C)	point (°C)
X	10	25
Y	50	90
Z	15	80

Identify the physical states of X,Y and Z t the temperature of 30°C.
Answer:
‘X’ is gas at the given temperatLire.
‘Y’ is solid at the given temperature.
‘Z’ is liquid at the given temperature.

Short Answer Type Questions 

Question 1.
Common salt and sugar hase similar appearance. Why are these classified as different substances?
Answer:
The substances are not classified only by their appearance. They are classified by their properties. such as density boiling point or melting point, conductivity ther mal capacit’ and other physical and chem ical properties. Common salt and sugar have diflì.rent physical and chemical prop erties and so are different substances.

Question 2.
Why do we sec water droplets collected on the outer surface of a glass container, containing Ice?
Answer:
The water vapour present in air, comes in contact with the cold outer surface of the container and gets condensed. This causes formation of water droplets.

Question 3.
liquids and gases can be compressed hut it is difficult to compress solids. Why?
Answer:
Liquids and gases have large intermolecular space. Thus on applying pressure externally on them, the molecules can corne more close, thereby minimising the space between them. But in case of solids there is no intermolecular space to do so.

Question 4.
If you open a bottle of perfume in one comer of a room, it immediately spreads throughout the room. Explain the properly insols-ed.
Answer:
The property involved is diffusion. In a gas, the particles arc free to mese an a chaotic motion at a great speed throughout its containing vessel. Thus, when you opcn a bottle of perfume in one corner, the particles of the perfume move at random motion in all directions and mix with othergas particles in the air. Thus, they reach instantaneously to our nose.

Question 5.
Why do people perspire a lot on a hot humid day?
Answer:
On a humid day. due to the heat, our body starts sweating for thecooling mechanism by evaporation. However, the humid air cannot hold any more water on a humid das and therefore the rate of evaporation decreases. Hence. sweat or perspiration is seen.

Question 6.
Hoss does the rate of diffusion change with (a) density of liquid and (b) temperature? Gise examples.
Answer:
(a) Rate of diffusion decreases with density of s liquid. Honey is denser than ink. If you add a drop of ink and honey ‘n two separate jars filled with water, it will be ohscned that honey takes longer time to reach the bottom of the jar than by the ink.

(b) Diffision increases with rise of iempersture. For example, liquids mix faster at higher temperaiures.

Question 7.
How do you differentiate between solids, liquids and gases on the basis of their inciting poInts 2nd boiling points?
Answer:

• Solids: They hase melting and boiling points abose room temperature.
• Liquids: They hase melting pointa below room temperature and boiling point abose room temperature.
• Gases: They have both melting and boiling points below room temperature.

Question 8.
Which property of the gas is utilised when natural gas is supplied for vehicles?
Answer: A gas is highly compressible and a large quantity of it can be compressed to a small volume. Therefore, natural gas is compressed and is supplied for use by vehicles in the form ofCNG (Compressed Natural Gas).

Question 9.
On a hot das, why do people sprinkle waler on (be roof or open ground?
Answer:
On a bot das, the surface of roof or ground absorbs large amount of heat and remains bot. On sprinkling water on these surfaces, the water absorbs large amount of heai from 11w surface due to its high laient heat of sapsietsation and ewaporates. thereby allowing the hot surface to cool.

Question 10.
Esplain how dIffusion nf gases In water is essenilal?
Answer:
The gases from the atmosphere diffuse and dissolve in water. Difluasion of gases like oxygen and carbon dioxide ¡n water is essential for tIse survival ni aquatic animals and plants! Aninsals breathe – in this oxygen dissolved in watet foe their survival and planis can use carbon dioxide
dissolved in water foe photosynthesis.

Question 11.
Why are liqnids and gases called fluids?
Answer:
Liquids and gases can flow. Liquids can flow from higher pressure to lower pressure. The gases flow in all available directions. Due to this property of flowing, both of them are called fluids.

Question 12.
On a hot day, why do we feel pleasant sitting under a tree?
Answer:
Trees have a lot of leaves which constantly show transpiration. Transpiration is the loss of water through tiny pores of leaves called stomata. When this water comes on the surface of leaf the water evaporates, thereby causing a cooling effect. Therefore, we feel pleasant sitting under the tree on a hot sunny day.

Question 13.
How is the high compressibilit property of gas useful to us?
Answer:
The gases have high compressibility. This property is used in the following
situations:

1. LPG is a fuel which is made up of petroleum gas. On compressing this petroleum gas. it forms liquid.
2. Oxygen cylinders in the hospitals have compressed gas filled in it.
3. CNG is a natural gas, which is compressed and used as a fuel in vehicles.

Question 14.
What ¡s pressure? What is its unit? On what factor does the pressure of a gas depend?
Answer:
The pressure exerted by a gas is the force exerted by gas particles per unit area on the walls of the container. It is expressed in pascal (Pa). I atmosphere 101325 x 10 Pa. The pressure depends on the average kinetic energy of the particles which depends on temperature of the gas.

Question 15.
How would you show that the three states of matter are interchangeable?
Answer:
On heating a solid substance and then cooling the vapour formed, we can show that the three states of matter arc interchangeable. Take ice cubes in a beaker and heat. Ice changes into water. On further heating, water changes into steam. On cooling, water vapour again changes into water and on further cooling water changes to ice.

Question 16.
Chee freezes at room temperature but mustard oil does not freeze even in winters. Which of these has a higher melting point and lower intermolecular forces?
Answer:
Ghee freezes at room temperature but mustard oil does not, it shows that intermolecular forces in ghee are stronger than those in mustard oil. The higher the intermolecular forces, the higher is the melting point. Therefore, ghce has a higher melting point than that of mustard oil.

Question 17.
Define evaporation.
Answer:
The phenomenon of change of a liquid into vapours at any temperature below its boiling point is called evaporation. Water, if left in an open vessel at room temperature, disappears after some time due to evaporation.

Question 18.
Is it true to say that fluorescent tubes contain only plasma?
Answer:
It is not correct to say that fluorescent tube contains only plasma. Inside a fluorescent tube there is helium gas or some other gas. The gas gets ionised or charged when electrical energy flows through it.

Analysing & Evaluating Questions

Question 19.
A sample of water under study was found to boil at 102°C at normal pressure. It the water pure? Will this water freeze at 0°C? Comment.
Answer:
(a) The given sample of water is not pure.
(b) The given sample of water will not freeze 0°C. The impurities raise the boiling point and lower the freezing point of water. Therefore, the given sample of water will freeze below 0°C.

Question 20.
A strong smelling gas ¡s stored in cylinders as liquid, but it comes out of the cylinder as gas.
(a) Name the gas.
(b) Vhat causes this change in state?
(c) Name the process of this conversion.
Answer:
(a) LPG (Liquefied Peroleum Gas).
(b) LPG gets converted into gas due to lowering of pressure.
(c) Vaporisation.

Long Answer Type Questions

Question 1.
Discuss the factors which affect evaporation.
Answer:
1. Surface area: Evaporation is a surface phenomenon. Thus, escaping of particles from liquid state to vapour state depends on surface area. Therefore, the rate of evaporation increases with surface area.

2. Temperature: If the temperature is increased, the rate of evaporation also increases. Due to increase in temperature, the particles gain more kinetic energy and change their phase from liquid to gaseous. Water will evaporate faster in sun than in shade.

3. Humidity: Humidity is the amount of water vapour present in the air. At a given temperature, air cannot hold more than a fixed amount of water vapour. Therefore, the rate of evaporation decreases with increase in the humidity of air.

4. Wind speed: With the increase in wind speed, the rate of evaporation increases. The particles of water vapour move away with the wind, decreasing the amount of water vapour in the surroundings.

Question 2.
How are particles of matter affected with increasing or decreasing pressure on the matter at a given temperature?
Answer:
On increasing pressure, particles of a matter come closer and move apart when pressure is reduced at a given temperature. Thus, if pressure is increasingly applied on a gas, particles of the gas come closer and closer and eventually the gas may change into liquid and then into solid form.

Question 3.
What is sublimation? With the help of an activity describe the sublimation of a solid substance. Name two substances used in our daily life that sublime on heating.
Answer:
We know that matter changes its state on heating from solid to liquid and from liquid to gas. However, there are some substances that change directly from solid state to gaseous state. This change of state from solid to gas without changing into liquid state is called sublimation. For example, camphor and ammonium chloride on heating change directly into vapour.

Activity

Take some ammonium chloride. Powder it and put in a china dish. Cover the china dish with an inverted funnel. Take some cotton and plug the stem of the funnel. Now, heat the china dish.
You will observe fine crystal particles depositing on the innerwalls ofthe funnel. Thus on heating, ammonium chloride is directly converted into ammonium chloride vapours which condense on the inner walls of the china dish.

Question 4.
Explain the diffusion of copper sulphate solution into water.
Answer:
The copper sulphate crystals dissolve slowly and form a layer of copper sulphate solution in the beaker. This blue copper sulphate solution diffuses into clear water and clear water diffuses down towards blue solution. This diffusion goes on until the whole water turns blue. So the spreading of blue colour is due to the diffusion of the blue copper sulphate solution and water into each other.

JAC Class 9 Science Important Questions