19/11/20

7. List the properties of air.

A.1. Air is colorless and odourless

    2. Air occupies space.

    3. Air has weight.

    4. Air expands on heating.

8. Name two effects of air pollution.

A. 1. Breathing problems like nose blocks, sneezing , wheezing etc

    2. Acid Rain- harmful gases released by the burning of fuels dissolve in rain water to form acid rain, which harms all living organism and pollutes land and water.

9. What are the uses of air?

A. Air is needed for birds and aeroplanes to fly, for burning, water vapour in the air is essential for water cycle and it is needed for breathing. In short life on Earth cannot exist without air.

10. List five causes of air pollution.

A. 1. Burning fuels in factories  and vehicles.

     2. Bursting firecrackers.

     3. Burning waste.

     4. Dumping of garbage which rots and releases gases.

      5. Spiting in public places.

Define the following:

1. Matter

A. Anything that has weight and occupies space is called a matter.

2. Breathing

A. The process of taking in and giving out air is called breathing.

3. Pollution

A. The addition of harmful substance to air, water or land is called pollution.

Home work:

Page No 72: A,B