Combustion and Flame A chemical reaction in which a substance reacts with oxygen to give off heat is called combustion. The substance that undergoes combustion is said to be combustible. It is also called fuel. The fuel may be solid, liquid or gas. … Read more
Coal and Petroleum Natural Resources Resources like air, water, soil, sunlight, coal, petroleum, natural gas and minerals are obtained from nature and are called natural resources. Inexhaustible natural resources Natural resources which are present in unlimited quantity in nature … Read more
Materials: Metals and Non-Metals Metals are lustrous, whereas non-metals have no lustre. The property of metals that allows them to be beaten into thin sheets is called malleability. Generally, metals are good conductors of heat and electricity, but non-metals are poor conductors. Generally, … Read more
Synthetic Fibres and Plastics Synthetic fibres – The synthetic fibres are made by human beings. That is why these are called synthetic or man-made fibre. A synthetic fibre is a chain of small units connected together. Many such small units of chemical … Read more
Microorganisms : Friend and Foe Microorganisms or microbes are very tiny organisms that can be seen only with the help of microscope. Major Groups of Microorganisms are – Bacteria, Fungi, Protozoa, Algae, Virus. Bacteria – Single celled. May be found in colonies. Can … Read more
Crop Production and Management In order to feed a large population – regular production, proper management and distribution of food is necessary. Crop – Same kind of plant grown and cultivated on a large scale to obtain food is called a crop. Example … Read more
Wastewater story Rich in lather, mixed with oil, the black-brown water that goes down the drains from sinks, showers, toilets and laundries is dirty. It is called wastewater. Cleaning of water is a process of removing pollutants before … Read more
Forest : Our Lifeline We get various products from the forest’s surroundings. A forest is a system comprising various plants, animals and micro-organisms. Different layers of vegetation provide food and shelter for animals, birds and insects. The various elements … Read more
Water: A Precious Resource We celebrate Water Day every year to attract everybody’s attention to the importance of conserving water. About 71% of the earth’s surface is covered with water. Water is found in three states: solid, liquid and gas. Water on … Read more
Light Light travels along a straight line. Any polished or glossy surface can act as a mirror. A mirror alters the direction of light that falls on it. This shift of direction by a mirror is … Read more
