Class 9 science

Living organisms require food for development, growth and health. India’s growing population of over one billion people demands more than a quarter billion tonnes of grain annually. Since cultivable land cannot be expanded significantly, increasing production efficiency through sustainable practices in agriculture and animal husbandry becomes essential while maintaining environmental balance. 12.1 Improvement in Crop […]

Sound is a mechanical form of energy that produces the sensation of hearing in our ears. It is produced by vibrating objects and travels as a wave through a material medium, carrying energy from one point to another. 11.1 Production of Sound Sound is produced whenever an object is set into vibration. Vibration is a

This chapter explains the scientific relationship between work, energy, and power. It clarifies how these terms, often used loosely in daily life, have specific mathematical definitions and units that help us understand the physical world. 10.1 Work In physics, work has a specific meaning that differs from mental or physical exhaustion. While studying for hours

This chapter explores gravitation and the universal law of gravitation formulated by Isaac Newton. It covers the motion of objects under the influence of gravitational force on earth, free fall, acceleration due to gravity, the difference between mass and weight, how weight varies from place to place, thrust and pressure, buoyancy, and Archimedes’ principle. Understanding

This chapter explores the causes of motion, introducing the concept of force and Newton’s three laws of motion. It covers balanced and unbalanced forces, inertia and mass, momentum, the mathematical formulation of laws of motion, and their applications in everyday life. Understanding these laws helps us explain why objects move or stay at rest and

This chapter introduces the concept of motion, explaining how to describe motion using distance, displacement, speed, velocity, and acceleration. It covers uniform and non-uniform motion, graphical representation of motion (distance-time and velocity-time graphs), equations of motion for uniformly accelerated motion, and uniform circular motion. Understanding motion helps us describe and predict the movement of objects

This chapter explains the concept of tissues, the difference between plant and animal tissues, various types of plant tissues (meristematic and permanent tissues including simple and complex), different types of animal tissues (epithelial, connective, muscular, and nervous), and their structure, location, and functions. Understanding tissues helps us learn how multicellular organisms achieve division of labour

This chapter explores the discovery of cells, their structure and organisation, the cell theory, different cell organelles and their functions, differences between prokaryotic and eukaryotic cells, and the processes of cell division (mitosis and meiosis). Understanding cells is crucial as they form the basic structural and functional units of all living organisms. Introduction While examining

This chapter explores the discovery of sub-atomic particles (electrons, protons, neutrons), the evolution of atomic models (Thomson’s, Rutherford’s, Bohr’s), electronic configuration, valency, atomic number, mass number, and isotopes and isobars. Understanding atomic structure is fundamental to chemistry and explains the behaviour of elements. Introduction In Chapter 3, we learnt that atoms and molecules are the

This chapter explains laws of chemical combination, Dalton’s atomic theory, the ideas of atoms, molecules, ions, and how to write chemical formulae and calculate atomic, molecular and formula unit mass. These ideas form the basic language of chemistry for higher classes. 3.1 Laws of Chemical Combination By the end of the 18th century, scientists clearly

This chapter explores the difference between pure substances and mixtures, explains types of mixtures (homogeneous and heterogeneous), and describes solutions, suspensions, and colloids. You will learn about concentration calculations, the Tyndall effect, and the classification of matter into elements and compounds with their properties. Introduction When we buy items like milk, ghee, butter, salt, or