Question

A. Fill in the blanks.

1. A fire cannot be lighted if there is no............... .

2. The air becomes................as we go ............... .
3. Contamination of atmosphere causes.................. pollution.
4. ................ impurities are left behind after evaporation.
5. ........................water is widely used in injections and medicines.
6. .................... travels through air.
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Answer 1

1.stick

2 ?

3.air

4. good

5 injected

6 sun rays

Answer 2

1. A fire cannot be lighted if there is no oxygen.

- Fire is a result of the combustion reaction, which mandatorily needs oxygen for it's occurance.

2. The air becomes thin as we go upwards.

- The density of the air is indirectly proportional with the altitude.

3. Contamination of atmosphere causes air pollution.

- Atmosphere contamination is caused by air pollution which also causes air pollution.

4. Water impurities are left behind after evaporation.

- During the evaporation of the water only the water molecules are greater than the other impurities are left over.

5. Distilled water is widely used in injections and medicines.

- Distilled water has no contamination which is ideal for medications.

6. Sound travels through air.

- Sound waves need medium of propagation which is mainly our atmospheric air.