Answer correctly.

1. The atmosphere extends up to ___________ above the Earth's surface.
   1. 2000 km
   2. 1800 km
   3. 1600 km
   4. 1400 km
2. In the troposphere, the temperature of air decreases with increase in height at the rate of 1° C for every ___________.
   1. 160 m
   2. 165 m
   3. 170 m
   4. 175 m
3. The atmosphere is held around the Earth due to the Earth's ___________.
4. The density of the Earth's atmosphere is ___________ near the Earth's surface.
5. The thermosphere is also called ___________.
6. In the mesosphere, the temperature of the air increases with increasing height. (True/False)
7. The exosphere is an extremely dense layer. (True/ False)

Answer correctly.

1. Which of the following is not a Greenhouse gas?
   1. carbon dioxide
   2. methane
   3. nitrogen oxide
   4. hydrogen
2. Some of the gases that prevent the heat of the Earth to escape into space are called ______________.
3. Depletion of the ozone layer has taken place because of the increase in the level of ______________ and ______________ in the lower atmosphere.
4. Oxygen protects us from the harmful ultraviolet rays of the Sun. (True/False)
5. Greenhouse gases are responsible for raising the atmospheric temperature. (True/False)

Picture Study

Observe the picture and answer the questions.

1. What is depicted in the picture?
2. How do you think it would affect our environment?

Place these words under the correct heading.

presence of ozone, about 80 km, weather conditions, radio communication, merges with space, no clouds, about 1600 km, densest layer, meteors, ions

What is the composition of the atmosphere?