Worksheet solutions for chapter: Natural Resources for class 9 are provided below.
(1) What is nitrogen cycle?
Ans- The Nitrogen Cycle is a biogeochemical cycle by which nitrogen is converted into multiple chemical forms of nitrogen which is circulated in atmosphere, marine and terrestrial ecosystem.
(2) What is ozone layer? What is the significance of it?
Ans – Ozone layer is a shield near to our atmosphere which absorbs ultraviolet rays of Sun.
Ozone layer is very useful for us. It absorbs ultraviolet rays that are very harmful. In absence of ozone layer, ultraviolet rays directly reach to us which will cause –
(i) Sun burn
(ii) Skin cancer
(iv) Weak immune system
(v) Plants can not survive in direct sun rays.
(3) How is the water returning to water bodies?
Ans- The whole process in which water evaporates and falls on the land as rain and later flows back into the sea via rivers is known as water cycle. Therefore, water returns back to water bodies.
(4) Can we reverse the soil erosion?
Ans- No, It is very difficult to reverse. But, we can save soil erosion by planting more trees and collecting rain water in dams.
(5) What are the natural resources?
Ans – Natural resources are resources which are available without human action.
Eg:- Land, Water and air.
(6) How to control air pollution?
Ans – Steps to control air pollution
(i) Use CNG or unleaded petrol for vehicles.
(ii) The solar energy, hydropower and wind energy should be used in place of fossil fuel.
(iii) More plants should be planted to lower the carbon dioxide in the atmosphere.
(7) What is the humus?
Ans – The dark brown organic material which is obtained from the decomposition of the leaves and animals waste is called humus. It gives nutrients to soil.
(8) What is the global warming and its consequences?
Ans – The temperature of earth‘s atmosphere is gradually increasing, this is called global warming. It happens because of the increase of co2 in the atmosphere. The co2 is released by the humans in breathing, burning coal and other fuels. Plants used carbon dioxide in photosynthesis. But co2 is increasing in atmosphere because of deforestation.
Effects of global warming
(a) It can cause sea levels to rise.
(b) Glaciers are melting because of the global warming.
(9) Why carbon is necessary?
Ans – Carbon is very important
(i) It is found in atmosphere as carbon – dioxide which is very useful for photosynthesis.
(ii) It is found in various minerals as carbonate and hydrogen-carbonate.
(iii) It is also found in all nutrients like proteins, carbohydrates, fats, nucleic acids and vitamins of our food.
(iv) The endoskeletons and exoskeletons of various animals are also formed from carbonate salts.
(10) What will be the direction of air which would flow at night in coastal areas?
Ans – At night water bodies and land starts to cool down. Water takes more time to cool in comparison of land. Therefore, air above water is warm and rises up and air above land is cool and it move from land to sea.