NCERT Solutions for Class 9 Science

NCERT Solutions for Class 9 Science have been solved and reviewed properly by the expert subject teachers. The comprehensive solutions provided in CBSEtuts.com will help you to ace the unsolved problems in the Class 9 Science book prescribed by the National Council of Education Research (NCERT) for all the schools affiliated to the Central Board of Secondary Education (CBSE).

Class 9 Science NCERT Solutions – Free PDF Download (All Exercises are Covered with Answers)

Chapter 1 Matter in Our Surroundings

In Chapter 1 Mattar in our surroundings, we learn  following : 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 minimum in gases. The spaces in between the constituent particles and kinetic
energy of the particles are minimum in the case of solids, intermediate in liquids and maximum in gases. The arrangement of 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. The states of matter are inter-convertible. The state of matter can be changed by changing temperature or pressure. Sublimation is the hange of solid state directly to gaseous state without going through liquid state. 

Chapter 2 Is Matter Around Us Pure

In Chapter 2 is Matter Around us pure, we learn following: A mixture contains more than one substance (element and/ or compound) mixed in any proportion. Mixtures can be separated into pure substances using
appropriate separation techniques. A solution is a homogeneous mixture of two or more substances. The major component of a solution is called the solvent, and the 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.

Chapter 3 Atoms and Molecules

During a chemical reaction, the sum of the 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 cannot 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. It shows all the properties of the substance. A chemical formula of a compound shows its constituent elements and the number of atoms of each combining element. Clusters of atoms that act as an ion are called polyatomic ions. They carry a fixed charge on them. The chemical formula of a molecular compound is determined by the valency of each element.

Chapter 4 Structure of the Atom

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. Neils Bohr’s 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.

Chapter 5 The Fundamental Unit of Life

The fundamental organisational 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 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

Chapter 6 Tissues

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 tissues are derived from meristematic tissue once they lose the ability to divide. They are classified as simple and complex tissues. Parenchyma, collenchyma and sclerenchyma are three types of simple tissues. Xylem and phloem are types of complex tissues. 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.

Chapter 7 Diversity in Living Organisms

Classification helps us in exploring the diversity of life forms. The major characteristics considered for classifying all organisms into five major kingdoms are:

1. whether they are made of prokaryotic or eukaryotic cells
2. whether the cells are living singly or organised into multi-cellular and thus complex organisms.
3. whether the cells have a cell-wall and whether they prepare their own food.

All living 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.

Chapter 8 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 motions of objects can be shown
through graphs.

Chapter 9 Force and Laws of Motion

Chapter 10 Gravitation

In this chapter 10 Gravitation Class 9 Science, we shall learn about gravitation and the universal law of gravitation. We shall discuss the motion of objects under the influence of gravitational force on the earth. We shall study how the weight of a body varies from place to place. We shall also discuss the conditions for objects to float in liquids.

Chapter 11 Work and Energy

In the previous few chapters we have talked about ways of describing the motion of objects, the cause of motion and gravitation.
Another concept that helps us understand and interpret many natural phenomena is ‘work’. Closely related to work are energy and power. In this chapter 11 Work Energy Class 9 Science we shall study these concepts.

Chapter 12 Sound

Everyday we hear sounds from various sources like humans, birds, bells, machines, vehicles, televisions, radios etc. Sound is a form of energy which produces a sensation of hearing in our ears. There are also other forms of energy like mechanical energy, light energy etc. We have talked about mechanical energy in the previous chapters. You have been taught about conservation of energy, which states that we can neither create nor destroy energy. We can just change it from one form to another. When you clap, a sound is produced. Can you produce sound without utilising your energy? Which form of energy did you use to produce sound? In this chapter 12 Sound Class 9 Science, we are going to learn how sound is produced and how it is transmitted through a medium and received by our ears.

Chapter 13 Why Do We Fall Ill

In this chapter, you will understand the details of health and diseases. Health and its significance, reasons about why we fall ill and much more. Important topics like distinctions between healthy and disease free person and Personal and community issues for health are included.

Chapter 14 Natural Resources

The chapter take you through the importance of the Breath of Life: Air. This topic is subdivided into topics such as the role of the atmosphere in climate control, how air moves (movement of air): winds, rain, air pollution.

Chapter 15 Improvement in Food Resources

This chapter explains you about Improvement in Crop Yields and other useful topics. How to make Improvement in food resources and livestock? The major groups of activities for improving crop yields –Crop production improvement, crop variety improvement, crop protection management.