Science (Chapter – 14) (Natural Resources) (Class – IX) Page 201

 Question 1:

What are the different states in which water is found during the water cycle?

Answer 1:

During the water cycle, water is found in solid state (snow, ice, etc.), liquid state (ground water,

river water, etc.), and gaseous state (water vapours).

Question 2:

Name two biologically important compounds that contain both oxygen and nitrogen.

Answer 2:

Two biologically important compounds that contain both oxygen and nitrogen are:

(i) Amino acids

(ii) Deoxyribonucleic acid (DNA) and Ribonucleic acid (RNA)

Question 3:

List any three human activities which would lead to an increase in the carbon dioxide content of air.

Answer 3:

(i) Burning of fuels in various processes like heating, cooking, transportation, and industry.

(ii) Human induced forest fires.

(iii) The process of deforestation includes the cutting down of trees. This decreases the uptake of

carbon dioxide for photosynthesis. Eventually, the content of carbon dioxide increases.

 Question 4:

What is the greenhouse effect?

Answer 4:

Some gases like carbon dioxide, methane, nitro us oxide prevent the escape of heat from the

Earth’s surface by trapping it. This increases the average temperature of the Earth. This is called the greenhouse effect. An increase in the content of such gases would lead to a situation of global warming.

Question 5:

What are the two forms of oxygen found in the atmosphere

Answer 5:

The two forms of oxygen found in the atmosphere are:

(i) Diatomic molecular form with chemical formula O2.

(ii) Triatomic molecular form with chemical formula O3 known as ozone