Free download NCERT Solutions for Class 9 Science Chapter 14 Natural Resources in PDF format. Class 9 Science NCERT Answers of all chapter in downloadable form are being provided so that students can use it offline also. NCERT Solutions for all subjects are given at one place.
NCERT Solutions for Class 9 Science Chapter 14
Class 9 Science Solutions – Natural Resources
Important Questions with Answers
- Question 1:
Explain the role of atmosphere in climate control.
- Answer 1:
Atmosphere maintains temperature of the earth suitable for the living organisms during day time and whole life. It prevents sudden increase in temperature during day time as well as night. Life does not exist on other planets due to absence of the atmosphere.
- Question 2:
What causes wind?
- Answer 2:
Uneven heating of air over land and water bodies causes wind.
- Question 3:
What is the importance of presence of green house gases in the atmosphere.?
- Answer 3:
They maintain the temperature of earth during day and night by absorbing infrared radiations of the sun.
- Question 4:
How are clouds formed?
- Answer 4:
(a) When water bodies are heated during day time, a large amount of water evaporates and goes into air.
(b) The hot air rises up carrying water vapours with it.
(c) As air rises, it expands and cools.
(d) This cooling causes the water vapour in the air to condense in the form of tiny droplets and form clouds.
- Question 5:
Why do organisms need water?
- Answer 5:
(i) Water in needed for all cellular activities.
(ii) Transportation of nutrients takes place with the help of water.
(iii) Plants require water for photosynthesis.
(iv) Our body contains 70% of water which maintains body temperature.
- Question 6:
Rivers from land, add minerals to sea water. Discuss how?
- Answer 6:
Rivers passes through land and rocks which contains minerals. The minerals get dissolved in water. Minerals are carried by the river to sea water.
- Question 7:
State two factors responsible for weathering of rocks.
- Answer 7:
(i) Uneven heating and cooling during day and night.
(ii) Flowing water breaks rocks into small pieces and take them along.
- Question 8:
How do lichen and mosses help in formation of soil?
- Answer 8:
Lichens and moss grow on rocks. They release substances (chemical) which breakdown the stones into fine particles resulting in the formation of soil. The mode of action is chemical.
- Question 9:
How is Carbon Dioxide fixed in atmosphere?
- Answer 9:
Plants take up carbon dioxide in photosynthesis to form carbohydrates. Carbon dioxide is returned to atmosphere by respiration in which carbohydrates produce carbon dioxide and water in the presence of oxygen. Carbon dioxide is also produced by the combustion of fossil fuels.
- Question 10:
Explain oxygen cycle.
- Answer 10:
The cycle by which oxygen is circulated continuously in the atmosphere by living and non-living organisms is called oxygen cycle.
(a)Human beings and animals take oxygen from the atmosphere and release carbon dioxide and water.
(b)The dead organisms also need oxygen for their decomposition.
(c)Plants take up carbon dioxide and water for photosynthesis and release oxygen in the atmosphere.
(d)We must grow plants so as to keep the atmosphere rich in oxygen.
- Question 11:
Explain the role of sun in the formation of soil. Justify. “Dust is a pollutant”.
- Answer 11:
Role of Sun: Sun heats up rocks during the day time by which they expands. During night, rocks cool down and contract. Since all the parts of rocks do not expand and contract at the same rate, this results in the formation of cracks and ultimately the huge rock breaks up into smaller pieces.
Dust as a pollutant:
(i) It suspends in air which can cause allergy and respiratory problems.
(ii) It covers stomata of plants and affects exchange of gases and retards plant growth.
(iii) It can causes irritation in eyes.
(iv) It can act as a carrier of vapours of lead and other heavier metals which are toxic.