Page 79 - Viva ICSE Science 4 : E-book

What to Do:
• Stretch the balloon and fi x it over the mouth of the empty
bottle as shown in the fi gure.
• Ask an elder to help you pour hot water into one of the bowls.
Similarly, pour cold water into the other bowl. Make sure not
to fi ll the bowls completely as the water may overfl ow in the
next step.
• Now, place the bottle in the bowl containing hot water for
some time and see what happens.

• Later, remove the bottle from the hot water and place it in hot water cold water
the bowl that contains cold water and observe. bowl bowl

Observation:
You will observe that the balloon starts blowing up when you put the bottle into the bowl
containing hot water. This is because hot water heats up the air inside the bottle. On being
heated, the air expands and blows up the balloon.
When you remove and put the bottle into the bowl containing cold water, the balloon shrinks
as the air inside the bottle cools and settles down.

Result:
This shows that air expands when it gets heated up.

ACTIVITY TIME

Air supports burning

Aim:
To show that air helps in burning
You Need:

A candle, a glass jar, a matchbox

What to Do:
• With the help of an elder, light a candle using matchstick.
• Cover the burning candle with a glass jar.
• Observe what happens.

Observation:
You will observe that after some time the candle blows off when it is covered with the glass jar.
This is because covering the candle with a glass jar cuts off the air supply.

Result:
This shows that air helps in burning.

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