CBSE Class 9 Science Natural Resource Worksheet Set 05

 

Answer : Pollutants are substances that cause pollution.

Oxides of nitrogen, suspended particles

 

Answer : Soil and water

 

Answer : To check soil erosion through water currents on the slopes.

 

Answer : Acid rain is a rain or any other form of precipitation that is unusually acidic. The main cause is the industrial burning of coal and other fossil fuels, the waste gases from which contain sulphur and nitrogen oxides which combine with atmospheric water to form acids.

 

Answer : South-west monsoon

North –east monsoon

 

 

Short Answer
 

Question : How does the atmosphere act as a blanket?
Answer : The atmosphere acts as a blanket by performing the following functions:
(a) It keeps the average temperature of the Earth fairly constant during day time and even during the course of whole year.
(b) It prevents a sudden increase in the temperature during day time.
(c) It slows down the escape of heat from the surface of the Earth into outer space during night time.

Question : How are clouds formed?
Answer : During the day time, water evaporates from water bodies and goes into the atmosphere.
Air also becomes hot due to sunlight and starts rising up taking along with water vapour.
As the air rises up, it expands and cools.
This cooling of air causes water vapour in the air to condense. The process of condensation of water occurs. Small droplets grow and become big by more and more condensation of other droplets of water.
These steps form the clouds.

Question : Why do organisms need water?
Answer : Organisms need water because:
Substances dissolve in water for reactions to take place Cellular processes need water for their functioning.
Transportation of substances within the body needs water.
Water helps in digestion of food and its absorption in the blood.
It helps to maintain body temperature.

Question : Do you know of any activity which may be polluting this water source?
Answer : The activities which may be polluting the water bodies are:
Disposal of garbage or sewage from cities/towns and from factories.
Release of hot water from the industries which may disturb the temperature of water body by disturbing the BOD.

Question : What is soil erosion?
Answer : Removal of top layer soil is known as soil erosion. It is rich in humus and nutrients. The agents of soil erosion are mainly flowing water or wind. Land becomes infertile if this process occurs for long time and the reason for the same is the loss of its valuable nutrients.