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JAC Class 9 Science Notes Chapter 6 Tissues

June 17, 2022June 16, 2022 by Bhagya

JAC Board Class 9th Science Chapter 6 Notes Tissues

→ A group of cells having a common origin and similar function are termed as tissues.

→ Plant tissues: They are primarily classified into two groups:
a. Meristematic tissues
b. Permanent tissues

Meristematic tissues: They are capable of dividing continuously to produce new cells. The meristematic tissues are present only at the growing regions such as shoot tip. root tip and at the base of intemodes and leaves.
JAC Class 9 Science Notes Chapter 6 Tissues 1
Depending on the area where they are present, meristematic tissues are classified as apical, lateral and intercalary. Meristematic tissues are very active, have dense cytoplasm, thin cellulosic walls and prominent nuclei. They lack vacuoles.

Permanent tissues: Formed from meristematic tissues, the cells in the tissue lose the ability to divide. They have differentiated and attained a permanent shape suitable for their functions. Permanent tissues are divided into two categories. Simple permanent tissues: Tissues which are made up of only one type of cells are called simple tissues.

Parenchyma, collenchyma and sclerenchyma are examples of simple tissues,
a. Parenchyma: Composed of unspecialised cells with relatively thin cell walls, large intercellular space, present in soft parts of the plant. Their main function is storage.
JAC Class 9 Science Notes Chapter 6 Tissues 2

b. Collenchyma: It is composed of living and elongated cells with cell walls and irregularly thickened at the comers. There is very little intercellular space. It provides mechanical support and elasticity to plant. It helps in bending of leaves and stems.

c. Sclerenchyma: It is composed of long, narrow and thick-walled cells. This tissue is made up of dead cells, and there are no intercellular spaces. Sclerenchyma cells are dead. They are present in seeds, nuts, husk of coconut- fibre of jute, etc.
JAC Class 9 Science Notes Chapter 6 Tissues 3

→ Complex permanent tissues: Made up of more than one type of cells (conducting tissues).
a. Xylem: It is composed of tracheids, vessels, xylem parenchyma and xylem fibres. Xylem conducts water and dissolves minerals from roots to all parts of the plant. Except xylem parenchyma, xylem cells are dead cells.
JAC Class 9 Science Notes Chapter 6 Tissues 4
b. Phloem: It conducts food from the green leaves/parts to other parts of the plant. It is composed of four elements-sieve tubes, companion cells, phloem parenchyma and phloem fibres. Except phloem fibres, phloem cells are living cells.

→ Animal tissues: Animal tissues are of four types in higher animals including human beings.
JAC Class 9 Science Notes Chapter 6 Tissues 6
a. Epithelial tissues: They are present for the covering of the external surfaces, internal cavities and organs of the animal body. Various types of epithelial tissues are:

Squamous epithelium in the lining of mouth and oesophagus.
Cuboidal epithelium in the lining of kidney tubules and salivary glands.
Columnar epithelium in the intestine and columnar epithelium with cilia in the lining of respiratory tract.
Glandular epithelium in the glands aids in a special function as gland cells, which can secrete at the epithelial surface.

b. Muscular tissues: They are made up of muscle cells, called muscle fibres. There are three types of muscle fibres:

Striated muscles (skeletal muscles or voluntary muscles): Cells are cylindrical, unbranched and multinucleate.
Smooth muscles (involuntary muscles): Cells are long, spindle-shaped and possess a single nucleus.
Cardiac muscles (involuntary muscles): Cells are cylindrical, branched and uninucleate.

c. Connective tissues: They connect various tissues and organs. They provide support to different parts of the body by forming packaging around different organs of the body. The different types of connective tissues in our body are bone, cartilage, tendon, ligament and blood.

d. Nervous tissues: The tissue responds to stimuli. The brain, spinal cord and nerves are composed of nervous tissues or neurons. A neuron consists of cell body, cytoplasm, nucleus, dendrite, axon and nerve ending. The neuron impulse allows us to move our muscles when we want to respond to stimuli.

JAC Class 9 Science Notes

JAC Class 9 Science Notes Chapter 5 The Fundamental Unit of Life

June 17, 2022June 16, 2022 by Bhagya

JAC Board Class 9th Science Chapter 5 Notes The Fundamental Unit of Life

→ All organisms consist of tiny building blocks which are known as cells. The term ‘cell’ was coined by Robert Hooke from the Latin word ‘cella’ which means a Tittle room’.

→ Cell is the basic structural and functional unit of all organisms. Cell is the lowest level of organisation that is ‘alive’.

→ Cell theory states that: All living organisms are composed of cells. Cell is the fundamental unit of life. All new cells arise from pre-existing cells.

→ Shape and size of cells: Cells vary in shape and size. They may be oval, spherical, rectangular, spindle shaped or totally irregular like the nerve cell. The size of cells also varies in different animals and plants. Most of the cells are very small in size, like red blood cells (RBCs), while some cells are fairly large, like nerve cells. Average size of a cell varies from 0.5 to 20 pm.

→ Cell Structure: Cell is a compound of same basic constituents.
1. Plasma membrane: Plasma membrane is the covering of the cell that separates the contents of the cell from its external environment. It is the living part of a cell. It is a very thin, delicate, elastic and selectively permeable membrane. As it is a selectively permeable membrane, it allows the flow of certain selected substances in and out of the cell. The plasma membrane is flexible and is made up of organic molecules called lipids and proteins. The flexibility of cell membrane also enables the cell to engulf food and other materials from its external environment. Such process is known as endocytosis. It is observed in Amoeba.

→ Transport of Substances through Plasma Membrane: Substances can pass through plasma membrane by two processes: diffusion and osmosis.
a. Diffusion: It is the process of movement of substances from their higher concentration to their lower concentration. During respiration, CO₂ is given out as a waste product and accumulates in higher concentration inside the cell as compared to the outside medium. Due to the difference in concentration inside and outside the cell, CO₂ starts moving out of the cell.

b. Osmosis: The movement of water moleculas through a selectively permeable membrane is called osmosis. Osmosis is the movement of water from a region of higher water concentration, through a semi-permeable membrane, to a region of lower water concentration.

→ If the medium surrounding the cell has a higher water concentration than the cell, the cell will gain water by osmosis. Such a solution is known as a hypotonic solution.
JAC Class 9 Science Notes Chapter 5 The Fundamental Unit of Life 1

If the medium has exactly the same water concentration as the cell, there will be no net movement of water across the cell membrane. Such a solution is known as an isotonic solution.
If the medium has a lower water concentration than the cell, it will lose water by osmosis. Such a solution is known as hypertonic solution.

→ Cell wall: Cell wall is a non-living, thick and freely permeable covering made up of cellulose. It is available in eukaryotic plant cells and in prokaryotic cells as well. It determines the shape of the cells. It protects the plasma membrane. It prevents desiccation or dryness in cells. It helps in the transport of various substances in and out of the cell.

→ Nucleus: Nucleus is covered by a double¬layered membrane. The fluid inside the nucleus is called nucleoplasm. Nucleus consists of chromosomes which are important for the functioning of a cell. Chromosomes consist of genes which are the carriers of genetic information. Nucleus controls all the metabolic activities of the cell. It is the storehouse of genes. Without nucleus, cell can neither survive nor show specialised activities.

→ Type of cells: The cells can be categorised in two types:

Prokaryotic cell: In some organisms, DNA and RNA (genetic substances) are bound by a membrane. This membrane bound nucleus is termed as true nucleus. Prokaryotic cells are the cells in which true nucleus and membrane bound organelles are absent. They are primitive and incomplete cells. Prokaryotes are always unicellular organisms. Bacteria and blue-green algae are examples of prokaryotes.
Eukaryotic cell: Eukaryotic cells are the cells in which true nucleus and membrane bound organelles are present. They are advanced and complete cells. Eukaryotes include all living organisms (both unicellular and multicellular) except bacteria and blue green algae.

JAC Class 9 Science Notes Chapter 5 The Fundamental Unit of Life 2

→ Protoplasm: It is a jelly-like, viscous, colourless semi-fluid substance present in various cell organelles in colloidal form. Protoplasm consists of two parts:

Cytoplasm: It is that part of protoplasm which surrounds the nucleus. It contains the various cell organelles.
Nucleoplasm: It is that part of protoplasm which is located inside the nucleus.

Protoplasm stores vital chemicals like amino acids, proteins, sugar, etc. It is the site of some metabolic reactions.
JAC Class 9 Science Notes Chapter 5 The Fundamental Unit of Life 3

→ Cell organelles: These are small membrane bound structures suspended in the cytoplasm. They perform lots of chemical activities to support the structure and functioning of a cell. Some cell organelles are described below:
1. Endoplasmic Reticulum: Endoplasmic reticulum is a mesh-like structure which is composed of numerous tubes. It extends from the plasma membrane to the nuclear membrane. There are two types of endoplasmic reticulum, viz, smooth ER (synthesises lipids, detoxify drugs) and rough ER (synthesises proteins). Rough ER has ribosomes on its surface which give it the characteristic rough appearance.
It serves as the transport channel in the cell. Substances are transported from cell membrane to cytoplasm and to nucleus and vice-versa. ER also serves the role of packing many substances in the cell. It helps in the formation of plasma membrane and Golgi-bodies. Smooth ER helps in synthesis and transport of lipids.
JAC Class 9 Science Notes Chapter 5 The Fundamental Unit of Life 4
2. Golgi body: The Golgi apparatus, first described by Camillo Golgi, consists of a system of membrane-bound vesicles arranged approximately parallel to each other in stacks called cistemae. The materials synthesised near the ER are packaged and dispatched to various targets inside and outside the cell through the Golgi apparatus. The Golgi bodies store, modify, pack and dispatch the substances. They help in the formation of lysosomes.
JAC Class 9 Science Notes Chapter 5 The Fundamental Unit of Life 5
3. Lysosomes: Lysosomes are small sac-like structures. They are derived from Golgi complex. Lysosomes contain digestive enzymes. They are found in eukaryotic cells, mostly in animals. Lysosomes help in digestion of foreign substances and wom-out cell organelles. They provide protection against bacteria and vims. They help to keep the cell clean. During the distribution in cellular metabolism, e.g., when they get damaged, lysosomes may burst and the enzymes digest their own cell. Therefore, lysosomes are also known as suicidal bags of a cell.

4. Ribosomes: These are extremely small, dense and round bodies interspersed in the cytoplasm. Ribosomes are made up of ribonucleic acid (RNA) and proteins. In prokaryotic cell, ribosomes are of 70 S type. In eukaryotic cells, ribosomes are of 80 S type. Ribosome is responsible for protein synthesis. They are not membrane bound.

5. Mitochondria: Mitochondria are small sausage-shaped organelles. It is a double-membrane structure. Outer membrane is smooth whereas inner membrane is projected into numerous finger-like structures called cristae. Mitochondria contain their own DNA and ribosomes. They provide energy for the vital activities of living cells. They produce energy due to chemical reactions, in the form of ATPs (Adenosine Triphosphate – energy currency of the cell). Therefore, it is called ‘powerhouse of the cell’.
JAC Class 9 Science Notes Chapter 5 The Fundamental Unit of Life 6

6. Centrosome and centrioles: Centrosome is found only in eukaryotic animal cells. It is not bounded by any membrane but consists of centrioles. Centrioles are hollow cylindrical structures arranged at right angle to each other and are made up of microtubules. Centrioles help in cell division and also help in the formation of cilia and flagella.

7. Plastids: Plastids are present in most of the plant cells and absent in animal cells. They are usually spherical or discoidal in shape. These are double membrane bound organelles. Plastids also have their own DNA and ribosomes. Plastids are of three types:

Chloroplast: They are green coloured plastids containing chlorophyll. Chloroplasts manufacture food by the process of photosynthesis.
Chromoplast: They are colourful plastids. They provide colour to flowers and fruits.
Leucoplast: They are colourless plastids. They help in the storage of various substances like starch, proteins and fats.

8. Vacuoles: Vacuoles are fluid filled chambers and are often seen in many cells. Vacuoles are very large in plant cells. A plant cell usually has a single but large central vacuole. Such a vacuole fills almost the entire space inside the cell. Vacuoles are much smaller and few in number in animal cells.
Cell division: A cell divides by one of the following two processes:
i. Mitosis: Each cell divides into two daughter cells and each new cell has same number of chromosomes as the mother cell.
JAC Class 9 Science Notes Chapter 5 The Fundamental Unit of Life 7
ii. Meiosis: Each cell divides into four daughter cells, each having half the number of chromosomes as the mother cell.

JAC Class 9 Science Notes

JAC Class 9 Science Notes Chapter 4 Structure of the Atom

June 17, 2022June 16, 2022 by Bhagya

JAC Board Class 9th Science Chapter 4 Notes Structure of the Atom

→ Atoms are made up of three fundamental particles or sub-atomic particles called electrons, protons and neutrons. Protons and neutrons of an atom are almost of same mass. The mass of proton is approximately 2000 times as that of an electron.

→ Electron (e): These negatively charged particles were discovered by J.J.Thomson in 1897. In the experiment, a gas at low pressure was taken in a discharge tube made up of glass.
JAC Class 9 Science Notes Chapter 4 Structure of the Atom 1

→ At the ends of the discharge tube, two electrodes were placed, connected to a battery for high voltage supply. The electrode connected to the negative end was known as cathode and that to the positive end as anode.

→ A stream of negatively charged particles was observed coming out of the cathode towards the anode. These particles were called electrons. The collection of negatively charged particles emitted from the cathode in the discharge tube are called cathode rays.

→ Proton (p⁺): In 1886, Goldstein observed in the same experiment, with different situation that, anode emitted positive particles which were called protons.

→ Canal rays: The positively charged radiations produced in the discharge tube from anode are called canal rays.

→ Difference between electron and proton:

Electron	Proton
Its mass is negligible.	Its mass is 1 unit.
Charge is negative.	Charge is positive.
J.J Thomson discovered it.	E. Goldstein discovered it.

→ Neutron (n): These neutrally charged particles were discovered by James Chadwick in 1932. Neutrons are present in atoms of all elements except hydrogen.

→ The structure of an atom:
1. Thomson’s Model of an atom: An atom is a positively charged sphere and the electrons are embedded in it. The magnitude of positive and negative charge is same inside an atom, so the atom is electrically neutral.
JAC Class 9 Science Notes Chapter 4 Structure of the Atom 2
2. Rutherford’s α-particle scattering experiment’: α-particles are doubly charged helium ions. Since they have a mass of 4 u, the fast moving α-particles have a considerable amount of energy. A thin gold foil with thickness of about 1000 atoms was taken. A lot of fast moving α-particles were bombarded on this thin gold foil. After passing through the foil, α-particles hit the screen.
JAC Class 9 Science Notes Chapter 4 Structure of the Atom 3

Following are the observations and inferences made:

Observation	Inference
a. Most of the α-particles pass through the foil without getting deflected.	a. Most of the space inside the atom is empty.
b. Some particles were deflected by small angles.	b. Positive charge of the atom occupies very little space.
c. One out of 12,000 particles rebound back.	c. All the positive charge and mass of the gold atom were concentrated in a very small volume within the atom.

Rutherford, on the basis of this experiment, suggested ‘the nuclear model of an atom’. According to the nuclear model of an atom:
a. Most of the space inside the atom is empty.
b. At the centre of an atom, a small, heavy, positively charged nucleus is present.
c. Electrons revolve around the nucleus.
d. Total positive charge in nucleus is the same as total negative charge on all electrons of the atom as atom has net zero charge.

→ Drawback of Rutherford’s model of an atom: If any charged particle undergoes accelerated motion, it must radiate energy. Therefore, if a charged body (e;) rotates around another charged body (nucleus), it will radiate energy. Due to energy loss through the radiation, speed of electrons will decrease and eventually jt will fall into the nucleus. But such collapse does not occur and atoms are found to be quite stable.

3. Bohr’s Model of Atom: In 1913, Neils Bohr overcame the limitations of Rutherford’s model and proposed a model of atomic structure.
Following are the postulates:
a. Electrons revolve around a centrally located heavy, small and positively charged nucleus in certain discrete orbits.
b. While revolving in discrete orbits, electrons do not radiate energy.
c. These discrete orbits or shells are called energy levels. These orbits or shells are represented by the letters K, L, M, N …
JAC Class 9 Science Notes Chapter 4 Structure of the Atom 4

→ Distribution of Electrons in Different Orbits: Distribution of electrons in different orbits (shells) is given by Bohr and Bury:
a. Maximum number of electrons present in a shell is given by 2n² (n = shell number).
For example,
n = 1 (K shell). 2n² = 2 (1)² = 2 electrons
b. The maximum number of electrons that can be accommodated in the outermost orbit is 8.
c. Electrons are not accommodated in a given shell, unless the inner shells are completely filled.

→ Atomic Number: The number of protons present in the nucleus of an atom is called its atomic number. It is denoted by Z.

→ Mass Number: Mass number is equal to the number of nucleons present inside the nucleus of an atom. It means, it is the sum of the total number of protons and neutrons of an atom. It is denoted by the letter A.
‘Mass number of element = Number of protons + Number of neutrons’
JAC Class 9 Science Notes Chapter 4 Structure of the Atom 6

→ Isotopes: Isotopes are atoms of same element having same number of protons but different number of neutrons. Isotopes have similar chemical properties but different physical properties.
For example: ¹²₆C, ¹⁴₆C

→ Uses of Isotopes:
a. An isotope of uranium (²³⁵₉₂C) is used in nuclear power plants to generate electricity.
b. An isotope of cobalt is used in treatment of cancer.
c. An isotope of iodine is used in treatment of goitre.
Isobars: Atoms of different elements having same mass number but different atomic numbers are called isobars.
For example: ⁴⁰₂₀Ca, ⁴⁰₁₈Ar

→ Valency: The electrons in the last shell of the atom are called valence electrons. These govern the chemical properties of elements. The number of valence electrons that take part in a chemical reaction is called valency of the atoms.
For example, hydrogen has only one electron in its outermost orbit, thus it requires one more electron to fill its outermost orbit (K shell). For this, hydrogen atom shares one electron with another hydrogen atom and forms Hr

→ When an electron from a higher energy level falls in an orbit of lower energy level, the difference in energy is radiated in the form of electromagnetic radiation or light. This explains why different atoms on heating or under other conditions emit light of different colours.

JAC Class 9 Science Notes

JAC Class 9 Science Notes Chapter 3 Atoms and Molecules

June 17, 2022June 16, 2022 by Bhagya

JAC Board Class 9th Science Chapter 3 Notes Atoms and Molecules

→ In 430 B.C., Democritus postulated that matter is made up of very small particles calLed “Atomos’ which means ‘indivisible’. Later, Antoine Lavoisier, from his experimental observations, established the laws of chemical combinations.

→ The Law of Conservation of Mass: This law of conservation of mass states that, the total mass of reactants is equal to the total mass of products.
For example:
A + B → C + D
(Reactants) → (Products)
Total mass of reactants = Total mass of products

→ Law of Definite Proportions: According to the law of definite proportions, in a chemical substance, the elements are always present in definite proportion by mass. For example. in water, the ratio of the mass of hydrogen to the mass of oxygen is always 1: 8.

→ After a series of experiments, Dalton concluded that all matter must be composed of tiny particles, which cannot be further divided. He called them atoms.

→ “The smallest particle of an element is called an atom.”
Atomic radius is measured in nanometer (nm).
1nm = 1 × 10⁹m
1 m = 10⁹nm
Atomic radii of hydrogen atom 1 × 10^-10 m

→ Dalton’s Postulates:

Matter is made up of atoms.
Atoms are indivisible and indestructible.
Atoms of a given element are identical in mass and in properties.
Compounds are formed by a combination of two or more same or different kinds of atoms and a chemical reaction is a rearrangement of atoms.
Atoms of different elements have different masses and chemical properties.
Atoms combine in the ratio of small whole numbers to form compounds.
The relative number and kind of atoms are constant in a given compound.

→ Elements and symbols: Dalton proposed a scheme of notation to represent elements.
JAC Class 9 Science Notes Chapter 3 Atoms and Molecules 1

→ Symbols for some elements as proposed by Dalton Symbols of some common elements

Name of the element	Latin name	Symbol
Hydrogen	–	H
Helium	–	He
Carbon	–	C
Copper	Cuprum	Cu
Cobalt	–	Co
Chloride	–	Cl
Cadmium	–	Cd
Boron	–	B
Barium	–	Ba
Bromine	–	Br
Bismuth	–	Bi
Sodium	Natrium	‘ Na
Potassium	Kalium	K
Iron	Ferrum	Fe
Gold	Aurum	Au
Silver	Argentum	Ag
Mercury	Hydrargyrum	Hg

→ Molecule: A molecule is a group of two or more atoms that are chemically bonded together and form the smallest part of an element or a compound. This can exist independently and shows all the properties of that substance.

→ Atomicity: The number of atoms constituting a molecule is referred to as its atomicity. Molecules of an element constitute same type of atoms. They may be monoatomic, diatomic or polyatomic.

Name of the element	Atomicity	Molecular formula
Helium	Monoatomic	He
Neon	Monoatomic	Ne
Argon	Monoatomic	Ar
Krypton	Monoatomic	Kr
Xenon	Monoatomic	Xe
Radon	Monoatomic	Rn
Hydrogen	Diatomic	H₂
Chlorine	Diatomic	Cl₂
Nitrogen	Diatomic	N₂
Phosphorus	Polyatomic (Tetra)	P₄
Sulphur	Polyatomic (Octa)	S₈

→ Ion: Ion is a charged particle and can be positively or negatively charged. A positively charged particle in a molecule is called cation, for example, Na⁺, Ca²⁺. An anion is a negatively charged particle in a molecule, for example, F^–, Cl^–.

→ Valency: The combining capacity of an element is known as valency. The combining capacity of the atoms to form molecules either with same or different elements is defined as valency. Valency is used to find out the number of atoms of an element that will combine with the atom of another element to form a chemical compound.

Every atom wants to become stable. To do so, it may lose, gain or share electrons.
a. If an atom consists of 1,2 or 3 electrons in its valance shell, then its valency is 1, 2 or 3 respectively, and it will lose 1, 2 or 3 electrons respectively.
b. If an atom consists of 5, 6 or 7 electrons in the outermost shell, then it will gain 3, 2 or 1 electron respectively, and its valency will be 3, 2 or 1 respectively.
c. If an atom has 4 electrons in the outermost shell, then it will share these electrons and hence its valency will be 4.
d. If an atom has 8 electrons in the outermost shell, then its valency is 0.
JAC Class 9 Science Notes Chapter 3 Atoms and Molecules 2

→ Variable valency: Some elements show more than one valency, hence, termed as variable valency elements.
For example:
Iron shows
valency II – Fe²⁺ (Ferrous ion)
valency III – Fe³⁺ (Ferric ion)

Copper shows
valency I – Cu⁺ (Cuprous ion)
valency II – Cu²⁺ (Cupric ion)

→ Chemical Formulae: The chemical formula of a compound is a symbolic representation of its composition.
Rule 1: Cross multiply the valency of elements to form a compound.
JAC Class 9 Science Notes Chapter 3 Atoms and Molecules 3

Rule 2: If compound consists of both metal and non-metal, then metal is written first. For example: In calcium chloride (CaCl₂) and zinc sulphide (ZnS), Calcium and Zinc are metals, so they are written first, whereas chloride and sulphide are non-metals.

Rule 3: If a compound is formed with polyatomic ions, then polyatomic ions are written in brackets.
For example: In aluminium sulphate [Al₂(SO₄)₃], the polyatomic sulphate ion, SO₄^2- is enclosed in a bracket before writing the subscript 3.
Here, the bracket with a subscript 3 indicates that three sulphate groups (SO₄^2-) are joined to two aluminium atoms.

Note: Compounds made up of a metal and a non-metal are called salts or ionic compounds. All the above examples are of salts.

→ Mole Concept: The quantity of a substance is expressed in terms of mole. 1 mole is also defined as the amount of substance which contains 6.022 × 10²³ units (Avogadro’s number denoted by NA).
For example 1 mole of oxygen atoms represents 6.022 × 10²³ atoms of oxygen and 5 moles of oxygen atoms contain 5 × 6.022 × 10²³ atoms of oxygen.

→ Molar Mass: The mass of 1 mole of a substance is called molar mass. Atomic mass or molecular mass in gram is equal to molar mass.
For example: Atomic mass of Fe is 56 u. Molar mass of Fe is 56 g.
Atomic mass of H₂O is 18 u. Molar mass of H₂O is 18 g.
Number of moles = \(\frac{\text { Given mass }}{\text { Molar mass }}\)

For example, number of moles in 122 g of iron will be
\(\frac{\text { Given mass }}{\text { Molar mass }}=\frac{112}{56}\) = 2 × 6.022 × 10²³ atoms.

JAC Class 9 Science Notes

JAC Class 9 Science Notes Chapter 2 Is Matter Around Us Pure

June 17, 2022June 16, 2022 by Bhagya

JAC Board Class 9th Science Chapter 2 Notes Is Matter Around Us Pure

→ A pure substance consists of a single type of particles.

→ A mixture has more than one substance (element / compound) mixed in any proportion.

→ Mixtures can be separated into pure substances by appropriate separation techniques.

→ A solution is a homogeneous mixture of two or more substances. The major component of a solution is known as the solvent and the minor one is the solute. For example, sugar dissolved in water or alloy of copper and zinc or ethyl alcohol in water.

Mass percentage of a solution
= \(\frac{\text { Mass of solute }}{\text { Mass of solution }}\) × 100
Volume percentage of a solution
= \(\frac{\text { Mass of solute }}{\text { Mass of solution }}\) × 100

→ Materials which are insoluble in a solvent and have particles which are visible to naked eyes form a suspension. A suspension is a heterogeneous mixture.

→ When solids are dispersed in liquids to form a heterogeneous mixture or an opaque medium, it is called suspension.

→ Colloidal solutions are heterogeneous mixtures where particles of 1 × 10⁹ to 1 × 10^-6 m diameter, called dispersed phase, are distributed uniformly in a solvent, called dispersing medium.

→ Difference between true solutions, suspension and colloidal solutions.

True Solution	ColloidalSolution	Suspension
It is a homogeneous mixture of solute and solvent.	It appears to be homogeneous but actually it is a heterogeneous mixture of dispersed phase and dispersing medium.	It is a heterogeneous mixture.
The solute particles are very small, i.e., less than 10⁹ m in diameter.	The solute particles are between 10⁹and 10⁶ m in diameter.	The solute particles are quite large, i.e., larger than 10⁶m in diameter.
Particles of true solution are not visible to naked eye.	Particles are not visible to naked eye but can be seen with ultramicroscope.	Particles are big enough to be seen by naked eye.
The entire solution passes through filter paper.	The particles can pass through ordinary filter paper.	The particles cannot pass through filter paper.
The solute particles do not show Tyndall effect.	The particles show Tyndall effect.	The particles may or may not show Tyndall effect.
The particles do not settle down.	The particles do not settle down.	The particles may settle due to gravity.

→ Different Types of Colloids
JAC Class 9 Science Notes Chapter 2 Is Matter Around Us Pure 1

→ Separation of a mixture can be done by hand-picking, sieving, winnowing, sedimentation, decantation, filtration, evaporation, distillation, fractional distillation, centrifugation, crystallisation and chromatography.

→ A physical change brings about a change in the state of matter without change in the composition or chemical nature of the substance.

→ A chemical change brings about a change in chemical properties of matter because one or more substances are transformed into a new substance.

→ Pure substances can be elements or compounds.

→ An element is a form of matter which cannot be broken down by chemical reactions into simpler substances.

→ A compound is a substance composed of two or more different types of elements, chemically combined in a fixed proportion.

→ Properties of a compound are different from its constituent elements whereas a mixture shows the properties of its constituting elements or compounds.
JAC Class 9 Science Notes Chapter 2 Is Matter Around Us Pure 2

JAC Class 9 Science Notes

JAC Class 9 Science Notes Chapter 1 Matter in Our Surroundings

June 17, 2022June 15, 2022 by Bhagya

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

→Matter: Everything in this universe is made up of material which is called matter. Matter is anything that has mass and occupies space. Matter is made up of lots of tiny particles.

→ Characteristics of particles of matter:
a. Particles of matter have space between them.
b. Particles of matter are continuously moving.
c. Particles of matter attract each other. Matter exists in three different states, viz., solid, liquic and gas.

Solid	Liquids	Gas
1. Strong intermolecular force of attraction.	1. Weak intermolecular force of attraction.	1. Very weak intermolecular force of attraction.
2. Very less intermolecular space.	2. Large intermolecular space.	2. Very large intermolecular space.
3. Have definite shape and volume.	3. No definite shape but definite volume.	3. No definite shape and volume.
4. High density, high melting and boiling points.	4. Density is lower, low melting and boiling points.	4. Density is very low.
5. Solids cannot be compressed.	5. Liquids can be compressed.	5. Gases are highly compressible.
6. Solids cannot flow.	6. Liquids can flow.	6. Gases can flow.

→ Matter can change its state from solid to liquid and from liquid to gas and vice-versa.
JAC Class 9 Science Notes Chapter 1 Matter in Our Surroundings 2

→ Effect of Temperature: On increasing temperature, the particles gain energy and start vibrating with greater energy. Due to increased kinetic energy, the particles overcome the force of attraction and a new state is obtained.

→ Melting Point: It is the temperature at which a solid becomes a liquid at atmospheric pressure. Boiling Point: It is the temperature at which a liquid changes into its vapour form at atmospheric pressure.

→ Latent Heat of Fusion: The amount of heat energy required to change 1 kg of a solid into liquid at its melting point is called the latent heat of fusion of the solid.

→ Latent Heat of Vaporisation: The amount of heat energy required to change 1 kg of a liquid into vapour at atmospheric pressure, at its boiling point is called the latent heat of vaporisation of the liquid.

→ Sublimation: It is the change of state directly from solid to gas or vice-versa without going through the liquid state. Evaporation: It is a surface phenomenon in which a liquid changes into vapour/gas below its boiling point. It results in lowering of temperature, i.e., cooling is caused when evaporation takes place.

→ Factors affecting Evaporation: An increase in surface area increases the rate of evaporation. An increase in temperature increases the rate of evaporation. A decrease in humidity increases the rate of evaporation. An increase in wind speed increases the rate of evaporation.

→ Some measurable quantities and their units:

Quantity	SI Unit	A Symbol
Temperature	kelvin	K
Length	metre	m
Mass	kilogram	kg
Weight	newton	N
Volume	cubic metre	m³
Density	kilogram per cubic metre	kg/m³
Pressure v	pascal	Pa

JAC Class 9 Science Notes

JAC Class 9 Science Notes in Hindi & English Jharkhand Board

December 22, 2022June 14, 2022 by Bhagya

JAC Jharkhand Board Class 9th Science Notes in Hindi & English Medium

JAC Board Class 9th Science Notes in English Medium

JAC Board Class 9th Science Notes in Hindi Medium

JAC Class 9 Science Important Questions and Answers in Hindi & English Jharkhand Board

January 11, 2023June 14, 2022 by Bhagya

JAC Jharkhand Board Class 9th Science Important Questions in Hindi & English Medium

JAC Board Class 9th Science Important Questions in English Medium

JAC Board Class 9th Science Important Questions in Hindi Medium

JAC Class 9 Science Solutions in Hindi & English Jharkhand Board

January 11, 2023June 14, 2022 by Bhagya

JAC Jharkhand Board Class 9th Science Solutions in Hindi & English Medium

JAC Board Class 9th Science Solutions in English Medium

JAC Board Class 9th Science Solutions in Hindi Medium

JAC Class 10 Social Science Notes Economics Chapter 5 Consumer Rights

June 14, 2022June 7, 2022 by Bhagya

JAC Board Class 10 Social Science Notes Economics Chapter 5 Consumer Rights

→ We the people participate in the market both as producers and consumers. As producers of goods and services we could be working in any of the sectors such as agriculture, industry, or services. Consumers participate in the market when they purchase goods and services that they need.

Rules and regulations are required for the protection of the consumers in the marketplace. Individual consumers often find themselves in a weak position.
Exploitation in the marketplace happens in various ways. For example, sometimes traders indulge in unfair trade practices, such as, when shopkeepers weigh less than what they should or when traders add charges that were not mentioned before, or when adulterated/defective goods are sold.
Markets do not work in a fair manner when producers are few and powerful whereas consumers purchase in small amounts and are scattered. This happens especially when large compnîes are producing these goods.

→ Consumer Movement

The consumer movement arose out of dissatisfaction of the consumers as many unfair practices were being indulged in by the sellers.
It vas presumed that it was a consumer’s responsibility while buying various products.
In Inda, the consumer movement as a ‘social force’ originated with the necessity of protecting and promoting the interests of consumers against unethical and unfair trade practices.
A major step taken in 1986 by the Indian government was the enactment of the Consumer Protection Act 1986, popularly known as COPRA.

→ Consumer Rights Safety is Everyone’s Right

We as consumers, have the right to be protected against the marketing of goods and delivery of services that are hazardous to life and property.
Many goods and services that we purchase, require special attention to safety. For example, pressure cookers have a safety valve which, if it is defective, can cause a serious accident. The manufacturers of the safety valve have to ensure high quality.
Information about goods and services: Consumers have the right to be informed about the particulars of goods and services that they purchase. Consumers can then complain and ask for compensation or replacement if the product proves to be defective in any manner. For example, if we buy a product and find it defective well within the expiry period, we can ask for a replacement. If the expiry period is not printed, the manufacturer will blame the shopkeeper and will not accept the responsibility.
In October 2005, the Government of India enacted a law, popularly known as RTI (Right to Information) Act, which ensures its citizens all the information about the functions of government departments.

→ Where should consumers go to get justice?

Consumers have the right to seek redressal against unfair trade practices and exploitation. If any damage is done to a consumer, he/she has the right to get compensation depending on the degree of damage.
Consumer forums: The consumer movement in India has led to the formation of various organisations locally known as consumer forums or consumer protection councils. They guide consumers on how to file cases in the consumer court. On many occasions, they also represent individual consumers in the consumer courts. These voluntary organisations also receive financial support from the government for creating awareness among the people.
Under COPRA, a three-tier quasi-judicial machinery at the district, state and national levels was set up for redressal of consumer disputes.
The district level court deals with the cases involving claims upto ₹ 20 lakh, the state level courts between ₹ 20 lakh and ₹ 1 crore and the national level court deals with the cases involving claims exceeding ? 1 crore.
If a case is dismissed in district level court, the consumer can also appeal in State and then in National level courts.
Thus, the Act has enabled us as consumers to have the right to represent in the consumer courts.

→ Learning to Become Well-Informed Consumers

The enactment of COPRA has led to the setting up of separate departments of Consumer Affairs in Central and State governments.
The posters are one example through which government spread information about legal process which people can use. You might also be seeing such advertisements on television channels.

→ Taking the Consumer Movement Forward

India has been observing 24 December as the National Consumers’ Day. It was on this day that the Indian Parliament enacted the Consumer Protection Act in 1986. India is one of the countries that have exclusive courts for consumer redressal.
Today there are more than 700 consumer groups in the country of which only about 20-25 are well organised and recognised for their work.
After more than 25 years of the enactment of COPRA, consumer awareness in India is spreading, but slowly.

JAC Class 10 Social Science Notes

JAC Class 10 Social Science Notes Economics Chapter 4 Globalisation and the Indian Economy

June 14, 2022June 7, 2022 by Bhagya

JAC Board Class 10 Social Science Notes Economics Chapter 4 Globalisation and the Indian Economy

→ Today’s consumers have a variety of choice of goods and services. Markets have been transformed vastly in a matter of few years.

→ Production Across Countries

Until the middle of the twentieth century, production was largely organised within countries.
Trade wa§ the main channel connecting distant countries.
Multinational corporations (MNCs) emerged. A MNC is a company that owns or controls production in more than one country.
MNCs set up offices and factories for production in regions where they get cheap labour and other resources. This is done to reduce the cost of production and the MNCs can earn greater profits.
MNCs not only sell their products globally but also produce the goods and services globally.
Production process is spread across the world witji cost optimisation.

→ Interlinking Production Across Countries

MNCs have set up production close to the markets; wherein skilled and unskilled labour is available at low costs and the availability of other factors of production is assured.
The money that is spent to buy assets, such .as land, building, machines and other equipment is called investment. Any Investment made by MNCs is called foreign investment.
At times MNCs set up production in collaboration with local companies. The benefit of the local companies is two¬fold: MNCs provide finance for additional investments. MNCs might bring with them the latest technology for production.
The most common route for MNC investments is to buy up local companies and then to expand production. Secondly, large MNCs in developed countries place orders for production with small producers of garments, footwear, sports items, etc. The products are supplied to MNCs, which then they sell under their own brand names to the customers. These MNCs have tremendous power to determine price, quality, delivery, and labour conditions for these distant producers.
MNCs are exerting a strong influence on production at these distant locations. Therefore, production in these widely dispersed locations is getting interlinked.

→ Foreign Trade and Integration of Markets

For a long time foreign trade has been the main channel connecting the countries. Trade routes connected India and South Asia to markets both in East and West, and extensive trade took place along these routes.
Foreign trade creates an opportunity for the producers to reach beyond domestic markets. Buyers have a wide option to choose from the imported goods produced in another country.
More choices of goods in the market and prices of similar goods in the two markets tend to become equal. Producers in the two countries closely compete against each other even though they are separated by thousands of miles.
Foreign trade, thus, integrates the markets in different countries.

→ What is Globalisation?

Globalisation is the process of rapid integration or interconnection between countries.
More and more goods and services, investments and technology are moving between countries. Globalisation has also encouraged movement of people between countries.

→ Factors that have Enabled Globalisation

Rapid improvement in technology has been one rpajor factor that has boosted the globalisation process. In the past fifty years, there have been several improvements in technology which have made faster delivery of goods across long distances possible at lower costs.
There have been huge advancements in information and communication technology. Information can be obtained and shared instantly.
The Indian government, after Independence had put barriers to foreign trade and foreign investment to protect the producers within the country from foreign competition. Starting around 1991, government removed the trade barriers. The time had come for the producers to compete with the producers around the globe. The government thought that this would enable the producers to impro ve’ the performance and the quality of the produce.
The goods could be imported or exported more easily and also foreign companies could set up factories and offices in India. This is known as liberalisation.

→ World Trade Organisation:

The aim of World Trade Organisation (WTO) is to liberalise international trade. Powerful international organisations believe that barriers to foreign trade and investment are harmful. Trade between the countries should be ‘free’.
WTO establishes rules of international trade and sees that these rules are followed. It is seen that the developed countries have unfairly retained trade barriers, while WTO has forced the developing nations to remove trade barriers.

→ Impact of Globalisation in India

Globalisation has affected the lives of the people and the economy in both positive and negative way.
MNCs have increased their investments in India over the past 20 years. MNCs have been interested in industries, such as cell phones, automobiles, electronics, soft drinks, fast food or service such as banking in urban areas. These products have large number of well-off buyers. In these industries, new jobs have been created. Local companies supplying raw materials, etc., to these industries have prospered.
Top Indian companies have benifited from increased competition as they have been able to invest in newer technologies and raise their production standards. Some have gained from the collaborations with foreign companies.
Few large Indian companies, such as Tata Motors, Infosys, Ranbaxy, Sundaram Fasteners, Asian Paints, etc., have emerged as multinationals themselves.
Governments in India are setting up special industrial zones, known as SEZs to encourage investments by foreign companies and help them establish their offices in India. Labour laws have been made flexible. Companies are allowed to hire workers on a temporary
basis, instead of on a regular basis. This lowers the cost of production and MNCs are able to make profits.
The jobs of workers are no longer secure. They do not have regular work. When they are employed, they have to put in long hours of work and also may have to do night shift. Their wages are low.
A large number of small producers had to shut down their units because of stiff competition from MNCs. They have been rendered jobless. Conditions of work in the organised sector have come to resemble the unorganised sector.

→ Struggle for a Fair Globalisation

Fair globalisation would create opportunities for all, and also ensure that the benefits of globalisation are shared better.
The government can play a major role in making globalisation fair. Its policies should protect not only the rich but also the poor and small producers in the country. The government can ensure that the labour laws are implemented and followed, and the labourers get their rights. It can support the small producers till they become capable of competing in the market with MNCs.
The government should ensure that the WTO rules are free and applied fairly across the world.