Free Natural Resources 03 Practice Test - 9th Grade
Wind is caused due to the differences in atmospheric pressure.
Solution : A
Gases and air molecules have a natural tendency to move from a region of high pressure to a region of low pressure and attain a uniform pressure throughout. When air above a region is heated, it starts rising up. As the air rises up, a low pressure region is created over that region. This will result in bulk movement of molecules of air from high pressure area to low pressure area which give rise to wind.
What are the processes involved in the formation of rain?
Solution : A
When water bodies are heated during the daytime, a large amount of water evaporates and goes into the air. This is called evaporation. The hot air rises up carrying water vapour along with it. As the air rises, it expands and cools. This phenomenon is called condensation. The condensation of water vapour results in the formation of clouds. These clouds are carried away with the help of wind and when they become heavy they fall down in the form of rain.
Which of the following is not a greenhouse gas?
Solution : D
∙ Greenhouse gases are gases that have the ability to trap heat energy. Gases like carbon dioxide, methane, ozone, etc., are examples of greenhouse gases that lead to a rise in the Earth's temperature. Increased concentration of these gases are responsible for global warming.
∙ Oxygen, on the other hand, is not a greenhouse gas.
From the statements given below, choose the human activities which cause water pollution .
Solution : A, B, C, and D
Water pollution occurs when pollutants are directly or indirectly discharged into water bodies without adequate treatment to remove harmful compounds.
Major causes of water pollution are:
1. Wastes from industries and sewage getting dumped into fresh water bodies.
2. Use of fertilisers and pesticides in farmlands.
3. Releasing water from dams into rivers which causes a variation of water temperature in rivers.
Which of the following gas causes ozone depletion?
Solution : C
Chlorofluorocarbon (CFC) is an organic compound that contains only carbon, chlorine, and fluorine. This compound does not get degraded by any biological process. CFC reacts with ozone layer and it results in the depletion of ozone layer.
Choose the areas where preventing of soil erosion is difficult.
Solution : B and C
Soil erosion can be easily prevented by afforestation. But it is very difficult to practice afforestation on mountains and hilly regions. The uneven terrain and steep slopes in these regions facilitate soil erosion. Areas with bare vegetation will not have the soil tightly held by the roots of plants. Hence, restoring soil erosion will be difficult in these areas.
What are the causes of soil pollution?
Solution : A, B, and C
The addition of harmful or toxic chemicals to the soil which renders it unproductive is called soil pollution.
1. The use of synthetic toxic chemicals such as pesticides, insecticides, fertilizers, which are used on plants, alters the nature of the soil and gradually decrease its productivity.
2. Industrial activities generate different kinds of wastes. Some of them are highly toxic in nature. The by-products are contaminated and are emitted into the land bodies nearby.
3. Waste materials are disposed of by the means of the landfill, which harmfully affects the fertility of the soil.
4. Acid rain, which is caused by air pollution, deposits acids in the soil through water runoffs. The acids are particularly harmful to the soil.
Choose the correct statements regarding greenhouse effect from the following.
Solution : A and B
The greenhouse gases do not let the radiations from the sun entering our atmosphere escape from the Earth. Thus it enhances the average surface temperature of the Earth which leads to global warming, i.e., an increase in the ambient temperature of the Earth causing several disasters.
The greenhouse gases responsible for greenhouse effect are:
- Water vapour
- Carbon dioxide
The biological oxidation of ammonia to nitrite is known as:
Solution : D
Nitrification is the biological oxidation of ammonia to nitrite followed by oxidation of nitrite to nitrate, performed by nitrogen fixing bacteria. It is a vital step in the nitrogen cycle and is essential for the survival of plant life.
Which of the following are the diseases that are caused due to breathing in air pollutants?
Solution : A, B, and D
- Unburnt carbon particles, oxides of nitrogen and sulphur, smog, etc., are the different pollutants that are present in the atmosphere. Studies have shown that regularly breathing air that contains any of these substances increases the incidence of allergies, cancer and heart diseases.
- Cholera is a water-borne disease caused due to contaminated water bodies.