Lesson-4 Air Around us

2. The layer of air in which weather changes take place

;

• Troposphere

• Stratosphere

• Ionosphere

• Exosphere

3. The layer of air where jet airplanes fly:-

• Troposphere

• Stratrosphere

• Ionosphere

• Exosphere

4. The _____ layer absorbs most of the harmful rays from the sun.

• Ozonelayer

• Troposphere

• Stratosphere

• Exosphere

5. Air is a mixture of gases. About 78% of the air is __________.

• Oxygen

• Carbondioxide

• Nitrogen

• Water vapour

6. Air contains a small amount of carbon-di-oxide , about _____%.

• 3%

• 0.02%

• 0.03%

• 0.04%

7. A medicine dropper and a doctor's syringe are examples of

• Air has space

• Air has weight

• Air has mass

• Air exerts pressure

8. Which air is needed for burning the candle?

• Carbond-di-oxide

• Oxygen

• Nitrogen

• Watervapour

9. As the air becomes thinner as you go higher,______ becomes more and more difficult.

• Breathing

• Standing

• Dancing

• Sitting

10. ______ layer send the radio signals back to the earth.

• Ozone layer

• Troposphere

• Stratosphere

• Ionosphere

1. Which of these gases in the air is important for plants to make food?

• Oxygen

• Carbondioxide

• Hydrogen

• Nitrogen