CLASS: X :: Chemical Reactions and Equations
CLASS: X NCERT (CBSE) SCIENCE Chemical Reactions and Equations Multiple Choice Questions Question 1: Which among the following is not a physical change? 1. Melting of solids to liquids 2. Vaporisation of liquids to gases 3. Liquefaction of gases to liquids 4. Decay of matter Answer: 4 Question 2: Which among the following is not a chemical change? 1. Melting of ice 2. Carbon cycle 3. Dehydration of substances 4. Fermentation of substances Answer:...
CLASS: VIII :: Reaching the age of Adolescence
CLASS: VIII NCERT (CBSE) Biology Reaching the age of Adolescence SUMMARY Changes During Puberty After the age of ten years, an individual becomes anadolescent, and experiences a lot of physical changes in the body.Adolescent is a general term for teenagers of both sexes.Adolescence is the period of life between the onset of puberty and reaching adulthood, that is, the period...
CLASS: VIII :: Reproduction in Animals
CLASS: VIII NCERT (CBSE) Biology Reproduction in Animals SUMMARY Sexual Reproduction in Animals Amoeba and bacteria adopt the asexual mode of reproduction.Reproductive organs in humans producegametes - eggs and sperms.A zygote is formed by the fusion of an egg and a sperm.The male reproductive organs include a pair of testes, two sperm ducts, and apenis.Sperms have a head, a middle piece and atail. Sperms contain...
CLASS: VIII :: Cell-Structure and Functions
CLASS: VIII NCERT (CBSE) Biology Cell-Structure and Functions SUMMARY Introduction to Cells With the help of a microscope, an English scientist,Robert Hooke, first discovered the existence of cells in 1665.Scanning electron microscopes are used to examine the external parts of various organisms.Thetransmission electron microscope is used to view the internal structure of a cell and its organelles. Organisms that are made up of a single...
CLASS: VIII :: Conservation of Plants and Animals
CLASS: VIII NCERT (CBSE) Biology Conservation of Plants and Animals SUMMARY Deforestation and Reforestation Deforestation is the clearing of forests to use the land for cultivation, building houses and factories, makingfurniture, and the construction of dams, or for using wood for fuel.Cases where human beings are responsible for deforestation are known as man-madecauses, while cases such as forest fires are known asnatural causes.Other causes...
CLASS: VIII :: Micro Oraganisms: Friend and Foe
CLASS: VIII NCERT (CBSE) Biology Micro Oraganisms: Friend and Foe SUMMARY World of Micro Organisms It'll be exciting to learn about microbes because we humans have microbes in our bodies, too. Living organisms invisible to the naked eye are calledmicroorganisms. Some microbes can be seen on bread with the help of a magnifying glass, while others are visible only under a microscope. Microorganisms are...
CLASS: VIII :: Crop Production and Management
CLASS: VIII NCERT (CBSE) Biology Crop Production and Management SUMMARY Agriculture The term crop is used to describe plants of the same kind that are grown and cultivated at one place in significant quantities. Plants that are planted during the rainy season are called kharif crops. Crops that grow during the winter season are called rabi crops. Many activities are performed before cultivating a crop,...
CLASS: VIII :: Pollution Of Air And Water
CLASS: VIII NCERT (CBSE) Chemistry Pollution Of Air And Water SUMMARY Air Pollution Substances that cause harmful changes in the air are called pollutants. Air pollution is caused due to the presence of pollutants in the air. Air pollution is caused by burning fossil fuels, like coaland petroleum, in industries, power plants andvehicles, and by burning of firewood and dung cakes. Pollutants are also released...
CLASS: VIII :: Combustion And Flame
CLASS: VIII NCERT (CBSE) Chemistry Combustion And Flame SUMMARY Combustion The chemical process in which a substance reacts withoxygen to give off heat is called combustion. A substance that undergoes combustion is called acombustible substance, or a fuel. Liquefied Petroleum Gas or LPG burns very quickly producing a lot of heat. This is called rapid combustion. When white phosphorous is left out in the open at room...
CLASS: VIII :: Coal And Petroleum
CLASS: VIII NCERT (CBSE) Chemistry Coal And Petroleum SUMMARY Natural Resources Resources supplied by nature are called natural resources. The sun, air, water, soil, trees and forests, wildlife, coal, petroleum, natural gas and minerals are all natural resources. Many industries, like fishing, mining, hunting, agriculture and forestry, revolve around the sensible use of natural resources. Natural...
