Class 9 Science NCERt
Chapter 1: Matter in our surroundings
This chapter gives information about Physical nature of matter, Characteristics of particles of matter, State of matter, The solid-state, the liquid state, the gaseous state, Can matter changes its state, Effects of change of temperature and pressure, Evaporation, Factors affecting evaporation, why should we wear cotton clothes in summer, why does a desert cooler cool better on a hot dry day, why do we see water droplets on the outer surface of a glass containing ice-cold water, etc.
The matter is made up of small particles. The matter around us exists in three states solid, liquid and gas. The forces of attraction between the particles are maximum in solids, intermediate in liquids and maximum in gases. The spaces in between the constituent particles and kinetic energy of the particles are minimum in case of solids, intermediate in liquids and maximum in gases. The arrangement of the particles is most ordered in the case of solids, in the case of liquids layers of particles can slip and slide over each other while for gases, there is no order, particles just move about randomly. Evaporation causes cooling. Boiling is a bulk phenomenon. Sublimation is the change of solid-state directly to the gaseous state without going through the liquid state. Evaporation is a surface phenomenon. The states of the matter are inter-convertible.
Chapter 2: Is matter around us pure
This chapter gives information about Mixture, Types of mixtures, What is a solution, Alloys, Filtration, Properties of a solution, Concentration of a solution, What is a suspension, What is a colloidal solution, Properties of a suspension, Properties of a colloid, Separating the components of a mixture, Immiscible liquids, Salt and camphor, How can we obtain different gases from air, Elements, compounds, and mixtures, etc.
A mixture contains more than one substance mixed in any proportion. Mixtures can be separated into purer substances using appropriate separation techniques. A solution is a homogenous mixture of two or more substances. The major component of a solution is called the solvent, and minor, the solute. The concentration of a solution is the amount of solute present per unit volume or per unit mass of the solution. Materials that are insoluble in a solvent and have particles that are visible to naked eyes form a suspension. A suspension is a heterogeneous mixture. Colloids are heterogeneous mixtures in which the particle size is too small to be seen with the naked eye, but is big enough to scatter light. Colloids are useful in industry and daily life. The particles are called the dispersed phase and the medium in which they are distributed is called the dispersion medium. Pure substances can be elements or compounds. An element is a form of matter that 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.
Chapter 3: Atoms and Molecules
This chapter gives information about Laws of chemical combination, Laws of conservation of mass, Law of constant proportion, Dalton atomic theory, What is an atom, Symbol of the atom, Atomic mass, Atomic masses, How to do atom exits, What is a molecule, Molecules of elements, Molecules of compounds, What is an ion, Writing chemical formulae, Molecular mass, and mole concept, Formula unit mass.
During a chemical reaction, the sum of all masses of the reactants and products remains unchanged. This is known as the law of conservation of mass. In a pure chemical compound, elements are always present in a definite proportion by mass. This is known as the law of definite proportions. An atom is the smallest particle of the element that usually exist independently and retain all its chemical properties. A molecule is the smallest particle of an element or a compound capable of independent existence under ordinary conditions. The chemical formula of a compound shows its constituent element and the number of atoms of each combining element. Mass of 1 mole of a substance is called its molar mass. One mole is equal to 12g of carbon.
Chapter 4: Structure of the Atom
This chapter gives information about Charged particles in matter, The structure of an atom, Thomson’s model of an atom, Rutherford’s model of an atom, Drawbacks of rutherford’s model of the atom, Bohr’s model of an atom, Neutrons, Different orbits, Atomic number, and atomic masses, Isotopes, Isobars.
Credit for the discovery of electron and proton goes to J.J Thomson and E.Goldstein, respectively. J.J Thomson proposed that electrons are embedded in a positive sphere. Rutherford’s alpha-particle scattering experiment led to the discovery of the atomic nucleus. Rutherford’s model of the atom proposed that a very tiny nucleus is present inside the atom and electrons revolve around this nucleus. The stability of the atom could not be explained by this model. Neil’s Bohr model of the atom was more successful. He proposed that electrons are distributed in different shells with discrete energy around the nucleus. If the atomic shells are complete, then the atom will be stable and less reactive. Valency is the combining capacity of an atom. The atomic number of an element is the same as the number of protons in the nucleus of its atom. The mass number of an atom is equal to the number of nucleons in its nucleus. Isotopes are atoms of the same element, which have different mass numbers. Isobars are atoms having the same mass number but different atomic numbers. Elements are defined by the number of protons they possess.
Chapter 5: The fundamental unit of Cell
This chapter gives information about Cell, Living organism, Structural organization, Plasma membrane, Cell membrane, Cell wall, Nucleus, Cytoplasm, Cell organelles, Endoplasmic Reticulum, Animal cell, Plant cell, Golgi apparatus, Lysosomes, Mitochondria, Plastids, Vacuoles, Cell division, Mitosis, Meiosis, etc.
The fundamental organizational unit of life is the cell. Cells are enclosed by a plasma membrane composed of lipids and proteins. The cell membrane is an active part of the cell. It regulates the movement of materials between the ordered interior of the cell and the outer environment. In-plant cells, a cell wall composed mainly of cellulose is located outside the cell membrane. The presence of the cell wall enables the cells of plants, fungi, and bacteria to exist in hypotonic media without bursting. The nucleus in eukaryotes is separated from the cytoplasm by a double-layered membrane and it directs the life processes of the cell. The ER functions both as a passageway for intracellular transport and as a manufacturing surface. The Golgi apparatus of stacks of membrane-bound vesicles that function in the storage, modification, and packaging of substances manufactured in the cell. Most plant cells have large membranous organelles called plastids, which are of two types – chromoplasts and leucoplasts.
Chapter 6: Tissues
This chapter gives information about What is a tissue, What is the utility of tissues in multi-cellular organisms, Simpler tissues, Permanent tissue, Simpler permanent tissue, Amoeba, Complex permanent tissues, Animal tissues, Epithelial tissue, Xylem, Phloem, Connective tissue, Muscular tissue, Nervous tissue, etc.
The tissue is a group of cells similar in structure and function. Plant tissues are of two main types- meristematic and permanent. Meristematic tissue is the dividing tissue present in the growing regions of the plant. Permanent tissue is derived from meristematic tissue once they lose the ability to divide. They are classified as simpler and complex tissues. Parenchyma, collenchyma, and sclerenchyma are three types of simple types of tissues. Xylem and Phloem are types of complex issues. Animal tissues can be epithelial, connective, muscular and nervous tissue. Depending on shape and function, epithelial tissue is classified as squamous, cuboidal, columnar, ciliated and glandular. The different types of connective tissues in our body include areolar tissue, adipose tissue, bone, tendon, ligament, cartilage, and blood. Striated, unstriated and cardiac is three types of muscle tissues. Nervous tissue is made of neurons that receive and conduct impulses.
Chapter 7: Diversity in Living Organism
Diversity in a living organism gives information about the basis of classification, Evolution, The Hierarchy of classification groups, monera, Protista, Fungi, Plantae, Animalia, The five-kingdom, Thallophyta, Bryophyta, Pteridophyta, Gymnosperms, Angiosperms, Dicot, Pinus, Animalia, Porifera, Coelenterata, Platyhelminthes, Nematoda, Annelida, Arthropoda, Mollusca, Echinodermata, Protochordata, Vertebrata, Cytlostomata, Pisces, Amphibia, Reptiles, Aves, Mammalia, Nomenclature, etc.
Classification helps us in exploring the diversity of life forms. The major characteristics considered for classifying all organisms into five majors kingdoms are a) Whether they are made of prokaryotic or eukaryotic cells b) whether the cells are living singly or organized into multi-cellular and thus complex organisms c) whether the cells have a cell-wall and whether they prepare their own food. All organisms are divided on the above bases into five kingdoms, namely Monera, Protista, Fungi, Plantae, and Animalia. The classification of life forms is related to their evolution. Plantae and Animalia are further divided into subdivisions on the basis of the increasing complexity of the body organization. Plants are divided into five groups: Thallophytes, Bryophytes, Pteridophytes, Gymnosperms, and angiosperms. Animals are divided into ten groups: Porifera, Coelenterata, Platyhelminthes, Nematoda, Annelida, Arthropoda, Mollusca, Echinodermata, protochordata and Vertebrata. The binomial nomenclature makes for a uniform way of identification of the vast diversity of life around us. The binomial nomenclature is made up of two words – a generic name and a specific name.
Chapter 8: Motion
Motion gives details about Describing Motion, Motion along a straight line, Uniform motion and non-uniform motion, Measuring the rate of motion, Speed with direction, Rate of change of velocity, Graphical representation of motion, Distance-time graphs, Velocity-Time groups, Equation of Motion by graphical method, Uniform circular motion.
Motion is a change of position; it can be described in terms of the distance moved or the displacement. The motion of an object could be uniform or non-uniform depending on whether its velocity is constant or changing. The speed of an object is the distance covered per unit time, and velocity is the displacement per unit time. The acceleration of an object is the change in velocity per unit time. Uniform and non-uniform motion of objects can be shown through graphs. If an object in a circular path with uniform speed, its motion is called uniform circular motion.
Chapter 9: Force and laws of motion
Force and laws of motion give information about Balanced and Unbalanced, First law of Motion, Inertia, and Mass, Second law of motion, Third law of motion, Conservation of momentum. The first law of motion: An object continues to be in a state of rest or uniform motion along a straight line unless acted upon by an unbalanced force. The natural tendency of objects to resist a change in their state of rest or of uniform motion is called inertia. The mass of an object is a measure of its inertia. Its SI unit is Kilogram. Force of friction always opposes the motion of objects. The second law of motion: The rate of change of momentum of an object is proportional to the applied force in the direction of the force. The SI unit of force is Kilogram meter per second squared. This is also known as newton and represented by the symbol of N. A force of one-newton products an acceleration of 1m/s2 on an object of mass 1kg. The momentum of an object is the product of its mass and velocity and has the same direction as that of velocity. Its SI unit is kgm/s1. Third law of motion: to every action, there is an equal and opposite reaction and they act on two different bodies. In an isolated system, the total momentum remains conserved.
Chapter 10: Gravitation
The law of gravitation states that the force of attraction between any two objects is proportional to the product of their masses and inversely proportional to the square of the distance between them. The law applies to the objects anywhere in the universe. Such a law is said to be universal. Gravitation is a weak force unless large masses are involved. The force of gravity decreases with altitude. It also varies on the surface of the earth, decreasing from the poles to the equator. The weight of a body is the force with which the earth attracts. The weight is equal to the product of masses and acceleration due to gravity. The weight may vary from place to place but the mass stays constant. All objects experience a force of buoyancy when they are immersed in a fluid. Objects having a density less than that of the liquid in which they are immersed, float on the surface of the liquids. If the density of the object is more than the density of the liquid in which it is immersed then it sinks in the liquid.
Chapter 11: Work and Energy
Life on the earth depends on resources like soil, water and air, and energy from the Sun. Uneven heating of air over land and water-bodies causes winds. Evaporation of water from water-bodies and subsequent condensation give us rain. Rainfall patterns depend on the prevailing wind patterns in an area. various nutrients are used again and again in a cyclic fashion. This leads t a certain balance between the various components of the biosphere. Pollution of air, water, and soil affect the quality of life and harm biodiversity. We need to conserve our natural resources and use them in a sustainable manner.
Work and Energy give information about Scientific conception of work, Work is done by a constant force, Energy, forms of energy, Kinetic energy, The greenhouse effect, The oxygen-cycle, Ozone layer, etc.
Chapter 13: Why do we fall ill
Health is a state of well enough to function well physically, mentally and socially. The health of an individual is dependent on his physical surroundings and his economic status. Diseases are classified as acute or chronic, depending on their duration. The disease may be due to infections or non-infections causes. Infectious agents belong to different categories of organisms and may be unicellular and microscopic or multicellular. The category to which a disease-causing organism belongs decides the type of treatment. Infections agents are spread through the air, water, physical contact or vectors. Prevention of diseases is more desirable than its successful treatment. Infections diseases can be prevented by public health hygiene measures that reduce exposure to infectious agents. Infectious diseases can also be prevented by using immunization. Effective prevention of infectious in the community requires that everyone should have access to public hygiene and immunization.
Chapter 14: Natural Resources
Life on the earth depends on resources like soil, water and air, and energy from the Sun. Uneven heating of air over land and water-bodies causes winds. Evaporation of water from water-bodies and subsequent condensation give us rain. Rainfall patterns depend on the prevailing wind patterns in an area. various nutrients are used again and again in a cyclic fashion. This leads to a certain balance between the various components of the biosphere. Pollution of air, water, and soil affect the quality of life and harm biodiversity. We need to conserve our natural resources and use them in a sustainable manner. Biogeochemical cycles areas 1)The water-cycles 2)The nitrogen cycle 3)The Carbon-cycle 3 i) The greenhouse effect ii) The oxygen cycle.
Chapter 15: Improvement In Food Resources
There are several nutrients essential for crops. of these, some are required in large quantities and are known as macro-nutrients whereas rest of the nutrients are required in small quantities are known as micro-nutrients. Manure and fertilizers are the main sources of nutrient supply to crops. Organic farming is a farming system with minimal or no use of chemicals as fertilizers, herbicides, pesticides, etc. and with a maximum input of organic manures, recycled farm wastes, and bio-agents, with healthy cropping systems. Mixed farming is a system of farming on a particular farm which includes crop production, raising of livestock, etc. Mixed cropping is growing of two or more crops simultaneously on the same piece of land. Growing two or more crops in definite row patterns is known as inter-cropping. The growing of different crops on a piece of land in pre-planned succession is called crop rotation. varietal improvement is required for higher yield, good quality, biotic and abiotic resistance, shortening the maturity duration, wider adaptability and desirable agronomic characteristics. Farm animals require proper care and management such as shelter, feeding, breeding and disease control. This is animal husbandry. Poultry farming is done to raise domestic fowls. poultry production includes egg production and broiler production for poultry meat. To enhance poultry production, crossbreeding is done between Indian and exotic breeds for variety improvement. Fish may be obtained from marine resources as well as inland resources. To increase the production of fish, they can be cultured in marine and inland ecosystems. Marine fish capture is done by fishing nets guided by echo sounders and satellites. Composite fish culture is commonly used for fish farming. Bee-keeping is done to get honey and wax.