Question

A deflated balloon fitted to the mouth of an empty bottle gets inflated as soon as the bottle is dipped halfway through into a bath of hot water. Which of the following could be inferred from this activity?

• A. Air expands on heating.
• B. Air expands on cooling.
• C. Hot air is lighter than normal air.
• D. Hot air occupies lesser space than normal air.

Answer 1

Answer: (A), (C)

The correct options are
A Air expands on heating.
C Hot air is lighter than normal air.

As shown in the figure below, when the bottle is fitted with a balloon at its mouth and dipped into a hot water bath, the balloon starts to inflate. This is because the air present in the empty bottle heats up because of the hot water surrounding the bottle. Hot air is lighter than normal air. So, it tries to escape out of the bottle thereby inflating the balloon.