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(Assessment of Learning Outcome)

A. Tick () the correct option :
1. Which one of the following gas protects us from the harmful rays of the sun?
(a) Oxygen (b) Carbon dioxide (c) Ozone (d) Argon
2. Which layer of the atmosphere is the most ideal for flying aeroplanes?
(a) Stratosphere (b) Thermosphere (c) Troposphere (d) Mesosphere

3. Which one of the following gases has the highest concentration in the air?
(a) Nitrogen (b) Oxygen (c) Ozone (d) Carbon dioxide
4. In which of the following layers the human beings live?
(a) Mesosphere (b) Stratosphere (c) Ionosphere (d) Troposphere

B. Fill in the blanks :
1. ________________ is the largest component and is essential for survival and growth of plants.
2. ________________ is the coolest layer in the atmosphere.
3. Stratosphere contains ________________ which absorbs the ultraviolet radiation of the sun.
4. Wind speed is measured by ________________.
5. Moisture in the air at any time is known as ________________.

C. Write ‘T’ for true and ‘F’ for false :
1. Our atmosphere is divided into three layers.
2. Our earth is surrounded by a huge layer of air, called atmosphere.
3. Without air the earth would be lifeless.
4. Green plants use hydrogen present in the atmosphere to make their food.
5. Troposphere’s average height is 13 km.

D. Answer these Questions :
1. Give a short account on the structure of the atmosphere.
2. Why is atmosphere important for us?
3. Write a note on the atmospheric layers of the earth.
4. Differentiate between weather and climate.
5. What do you mean by air pollution? Why is it harmful for us?

Life Skills and Value (Activity)

• Prepare a big chart showing different layers of the atmosphere. Show it in your class.
• Make a project on “Causes and effects” of Air Pollution.

Social Studies-7 21