CBSE Class 9 Science Natural Resource Worksheet Set F

 

Answer : Smog is a yellowish or blackish fog formed mainly by a mixture of pollutants in the atmosphere which consists of fine particles and ground-level ozone. Smog which occurs mainly because of air pollution can also be defined as a mixture of various gases with dust and water vapor.

 

Answer : Biotic component

Abiotic component

 

Answer : Fresh water and marine water.

 

Answer : A biochemical cycle refers to the natural cycle of the earth through which a chemical substance or matter moves through the biotic and abiotic components of the earth. These components always interact with each other and form a stable system in the biosphere.

 

Answer : Unburnt carbon particles or hydrocarbons suspended in air.

 

 

Question : How is our atmosphere different from the atmosphere on Venus and Mars?
Answer : The main difference is the composition of both the atmosphere .The atmosphere of Earth contains a mixture of many gases like nitrogen (78.08%), oxygen (20.95%), carbon dioxide (0.03%) and water vapour (in varying proportion). On the other hand, the atmosphere on Venus and Mars mainly contains carbon dioxide. i.e., about 95-97%. It may be the
reason that there are no life in the existence in both Venus and Mars.

Question : What causes winds?
Answer : Unequal heating of atmospheric air generates the winds.. The heat causes rising up of air along with water vapour. As the air rises, it expands and cools. This cooling causes the water vapour in the air to condense. The condensation of water occurs if some particles (like dust particles) act as the ‘nucleus’ for these drops to stick around. These tiny
droplets grow bigger by more and more condensation of other water droplets and finally form the clouds.

Question : List any three human activities that you think would lead to air pollution.
Answer : The following activities lead to air pollution:
Excessive burning of fossil fuels, i.e., coal and petroleum produces high amount of oxides of nitrogen and sulphur.
Many industries release high amount of poisonous gases into the atmosphere causing air pollution.
Question : What is the major source of freshwater in the city/town/village where you live?
Answer : Underground water is the major source of water in city/town/village,. It is drawn with the help of hand pumps and tubewells.
The other nearby sources are rivers, lakes and ponds.

Question : How is soil formed?
Answer : The formation of soil takes place in the following ways:
Rocks near the surface of Earth are broken down by various physical, chemical and some biological processes. This process takes millions of years.
This weathering leads to the formation of fine particles called soil.
There are some other factors responsible to the formation of soil.
These are:
Cracking and breaking down of rocks by sun heat that causes them into small particles.
Water dissolves rocks by freezing and fast flowing.
Wind causes erosion of rocks by fast blowing.
Lichens and mosses grow on rock surfaces and break them into powder down and form a thin layer of soil.

Question : What are the methods of preventing or reducing soil erosion?
Answer : Preventive methods of soil erosion are as follows:
Afforestation
Contour Ploughing
Step (terrace) Farming
Soil Cover
Overgrazing