What are the different states in which water is found during the water cycle?
Water is found during the water cycle in three states, namely solid (ice or snow), liquid and vapour.
What is green house effect?
The increase in the temperature of the Earth due to the increase in the concentration of gases like Caarbon-dioxide , methane etc is called green house effect. It is the heating of the atmosphere due to the absorption of infrared radiations by CO2 molecules.
Name two biologically important compounds that contain both oxygen and nitrogen.
Proteins and nucleic acids (DNA and RNA) are the two biologically important compounds that contain both oxygen and nitrogen.
What are the methods of preventing or reducing soil erosion.
The following are some methods which can prevent or reduce soil erosion:
(i) Keeping the vegetation cover on the ground which reduces soil erosion by wind and water.
(ii) Avoid overgrazing.
(iii) Afforestation, the roots of trees check the flow of running water. Trees also check speed of strong winds. Thus, prevent erosion of soil.
(iv) Intensive cropping.
List any three human activities which would lead to an increase in the carbon dioxide content of air.
The following activities of human beings may increase carbon dioxide content of air:
(i) Burning of fossil fuels such as petrol, diesel and coal in various activities like transportation and industrial processes.
(ii) Burning of wood and charcoal for heating, cooking, etc.
(iii) Deforestation that reduces the green plant and tree population, consequently utilisation of atmospheric CO2 during photosynthesis.
Switch
