CBSE Class 8 MCQs, Notes, PDF Book,Solutions, Important Questions, & Previous Year Papers, Sample Papers

What is air? Air is a combination of different gases that form the atmosphere of the Earth. The constituents of air are nitrogen (78%), oxygen (21%), water vapour, carbon dioxide and other gases such as helium, ozone, argon etc (0.04%) along with dust particles, pollens and spores. This constituent of air may vary on other […]

Celestial bodies The Universe includes all the stars, planets and galaxies and its size is unknown. However, there is a spherical region of the universe that can be observed from the Earth which is called Observable Universe. This Observable Universe comprises of different physical objects that occur naturally on their own. These objects are called […]

What makes things visible? We can see the world through our eyes or our sense of sight. However, we cannot see anything without the light, that is, in darkness. When light falls upon or is emitted by an object our eyes detect that light and hence the object becomes visible to us.       […]

A Natural Phenomenon is anything that occurs on its own in nature without any kind of human intervention. For example, the weather of a place, fog, storms, winds, tides, volcanic eruptions and cyclones all can be categorized as natural phenomena. Some natural phenomena can be destructive such as cyclones, thunderstorms, lightning and earthquakes. However, there […]

Conductors and insulators                       Figure 1 Conductors and Insulators of Electricity 1. A conductor is any material or substance that allows electricity to flow through it. 2. An insulator is any substance or material that prevents the flow of electricity through it. 3. Any substance […]

What is sound? A sound is a form of energy that is produced when air molecules vibrate in a particular pattern called waves. Hence, the sound is a wave. Vibration can be described as a back and forth motion of an object. Depending upon the vibrations, a sound is produced. Sound cannot be produced without […]

What is Friction? Friction is a force that comes into play when two surfaces come in contact with each other. The Frictional force or the force of Friction acts in the opposite direction of the motion of the object. The force of Friction opposes the relative motion between the surfaces of two moving objects.   […]

What is a Force? When a push or pull is applied to an object it is called force. A force can change the state of an object from rest to motion or vice versa. To let a force come into play, two or more objects must interact with each other.           […]

Adolescence and Puberty Animals, as well as human beings, can reproduce only after a certain age or time period in their lives after growing up into an adult. This is because of changes in hormones in their bodies that make them capable of reproduction. What is adolescence? It is a time period in life when […]

a) Several processes such as circulation of blood, digestion and respiration are essential for the survival of human beings and other animals. b) Similarly, reproduction is essential to maintain the continuity in the species. c) If reproduction in animals does not take place, no similar kind of organisms will be present on the earth generation […]

A Cell (from Latin cella, meaning “Small Room”) is the basic Structural, Functional, and Biological unit of all known Living Organisms. A cell is the Smallest Unit of life that can replicate independently, and cells are often called the “Building Blocks of Life”. Discovery of the Cell    Figure1: Robert Hooke discovered cells in 1665 […]

Biosphere: Part of the Earth that supports life is called the biosphere. It is here that all living organisms exist. Biodiversity: Variety of organisms that exist on the Earth, their interrelationships, and their relationship with their environment is called the Biological Diversity and the Biodiversity. Wildlife Sanctuary: This is a protected area where animals can […]

  Remember, when we burn magnesium ribbon in air, it produces heat and light and we get magnesium oxide. Chemical Equation for Burning of Magnesium Magnesium + Oxygen → Magnesium Oxide + Heat and Light 2Mg + O2 →  2MgO + ∆ Similarly, when we burn charcoal in air, it produces carbon dioxide, heat and […]

                                           Figure 1 Classification of Resources Coal, Petroleum and Natural Gas are exhaustible natural resources. They are fossil fuels. Fossil fuels are fuels that are formed by fossils (or dead remains) of living organisms. What […]

Metals and Non-metals differ in terms of their physical and chemical properties. Physical Properties of Metals and Non-metals Physical Properties Metals Non-Metals Conductivity Metals (such as iron or copper) are good conductors of heat and electricity. Non-metals (such as coal or sulphur) are poor conductors of heat and electricity. Graphite is an exception as it […]

Chapter 1 Crop Production and Management Chapter 2 Microorganisms: Friend and Foe Chapter 3 Synthetic Fibres and Plastics Chapter 4 Materials: Metals and Non-Metals Chapter 5 Coal and Petroleum Chapter 6 Combustion and Flame Chapter 7 Conservation of Plants and Animals Chapter 8 Cell Structure and Functions Chapter 9 Reproduction in Animals Chapter 10 Reaching […]

Fabrics are made by weaving fibres (or threads) obtained from natural or artificial sources. They can be of two types: What are Synthetic Fibres? What is a synthetic fibre made up of? A synthetic fibre, as well as plastic, is made up of a chain of small units (called Monomers) which combine to form polymers. […]

What are Microbes? Microbes or microorganisms are tiny organisms which are so small that we cannot see them with an unaided eye. Some microorganisms can be seen with the help of a magnifying glass (such as fungus that grows on bread) while some can only be seen when you use a microscope (such as bacteria […]

Why do we need food? We need food because it gives us energy, keeps us healthy, and helps us to grow as well as repair and replace damaged and worn-out tissues. How do plants and animals get their food? Most plants make their own food through the process of Photosynthesis. Animals feed on plants or […]