chapter 12:Life supports

1. ...............is a method which separates impurities from water.

• Sedimentation

• deforestation

• Distillation

• decantation

• Filteration

2. Which is the 3rd layer of the atmosphere?

• stratosphere

• troposphere

• exosphere

• mesosphere

• Thermosphere

3. The amount of water vapour present in the air is called...............

• nitrogen

• argon

• oxygen

• Humidity

4. Air needs_________for burning.

• matchsticks

• nitrogen

• carbon

• oxygen

5. Clean air consist of 78 per cent of ______________.

• nitrogen

• carbon

• argon

• oxygen

6. water is safe for drnking after ..........

• filtration

• sedimentation

• chlorination

• distillation
  
  

7. which is the fourth layer of the atmosphere ...............

• mesosphere

• thermosphere

• exosphere

• troposphere

• stratosphere

8. the most important gas for survival is ?

• argon

• oxygen

• carbon dioxide

........... is an important gas for plants

• carbon dioxide

• nitrogen

• oxygen

in which layer does weather occur

• troposphere

• stratosphere

• thermosphere