Answer the questions given by choosing the most appropriate alternative.

1. Radio waves transmitted from the Earth are reflected back to the Earth in _________________.
   1. troposphere
   2. stratosphere
   3. mesosphere
   4. thermosphere
2. The ozone layer is a part of _________________.
   1. stratosphere
   2. troposphere
   3. thermosphere
   4. mesosphere
3. The troposphere has the largest concentration of _____________.
   1. oxygen
   2. nitrogen
   3. water vapour
   4. atom
4. _________________, a trillion-ton iceberg, has broken off from Antarctica's Larsen C ice shelf.
   1. A-68
   2. A-69
   3. A-70
   4. A-67
5. The mesosphere extends up to a height of _____________ km.
   1. 80
   2. 90
   3. 70
   4. 75

Fill in the blanks.

1. Layer of gases which envelops the Earth is called _________________.
2. Air contains a variable amount of _______________, about 1 to 4 per cent.
3. The upper limit of mesosphere is called the _______________.
4. The layer of atmosphere where airplanes fly is called ______________.
5. Meteors burn on entering the atmosphere in the presence of ______________.

Write (T) for true and (F) for false.

1. The atmosphere makes life possible on Earth.
2. Troposphere has high night-shining (noctilucent) clouds.
3. Temperature increases with altitude in the troposphere.
4. The air resting over the poles is dense and heavy.
5. Jet planes move in the mesosphere.

Differentiate between Oxygen and Carbon dioxide.

Differentiate between Ozone layer and Atmosphere.