Available Answers

1. 1.

   Fill in the blanks.

   1. Seventy-eight percentage of the atmosphere is made up of _______________________, and twenty-one percentage is made up of ______________.
   2. _______________ and _________________ are two inert gases found in the atmosphere.
   3. The _________________ is the densest layer of the atmosphere.
   4. The ozone layer blocks the _________________________ from reaching the surface of the Earth.
   5. Heavy use of synthetic fertilizers in agriculture releases _____________________ into the atmosphere.
2. 2.

   Tick the sentences that are true. Correct the others.

   1. As we move outwards from the Earth's surface, the atmosphere gradually becomes thicker.
   2. Air temperature increases steadily with altitude.
   3. The mesosphere lies above the stratosphere.
   4. Greenhouses are called so because they are painted green in colour.
   5. The use of fossil fuels increases greenshouse gases in the atmosphere.
3. 3.

   Temperature increases with height in the stratosphere. Give reasons.

4. 4.

   The troposphere is also known as the 'weather-making layer'. Give reasons.

5. 5.

   The ozone layer is vital for life on the Earth. Give reasons.

6. 6.

   There is a gradual depletion of the ozone layer.  Give reasons.