1. Air in our lives

Question 1

The earth is surrounded by the _________________.

Answer 1

atmosphere

Question 2

Air is all around us. Properties of air:

Answer 2

1. Cannot be seen
2. Does not have a taste
3. does not have a smell

Question 3

What gases is air made up of?

Answer 3

1. Nitrogen (78%)
2. Oxygen (21 %)
3. Others (1%)
   - carbon dioxide
   - water vapour
   - helium

Question 4

When we fill the ballon with air, it gets _________ and it cannot be

Answer 4

bigger
pressed completely flat

Question 5

When we let the air out, the balloon gets

Answer 5

smaller.

Question 6

Air ________ spaces.

Answer 6

takes up

Question 7

Air does not have __________

Answer 7

a fixed shape.

Question 8

Hot air ____________.
Cool air ____________.

Answer 8

rises
sinks

Question 9

The movement of air forms _________

Answer 9

wind.

Question 10

Describe the formation of wind.

Answer 10

1. During the day, the land surface is warmer than the sea surface.
2. The warmer air over the land rises.
3. The cooler air over the sea sinks and flows towards the land to replace the rising air.
4. At night, sea surface is warmer than the land surface so air flows from the land towards the sea.

Question 11

Wind is useful to us. Example:

Answer 11

1. it helps to dry our clothes
2. it can be used to generate electricity

Question 12

Strong winds cause ___________ and may _______ us.

Answer 12

damage
hurt