Question

Water at ${{0}^{o}}C$ is taken to the moon in a bottle. When bottle is opened water will:
(A). Freeze
(B). Remains as such
(C). Boil
(D). Lose temperature

Answer 1

Hint: As we take water from the Earth to the moon, the external pressure around it changes and hence its properties also changes. There is no atmosphere on the moon and hence there is no atmospheric pressure. For bodies to be stable, the internal pressure must be equal to the external pressure.

Complete solution:
The atmosphere is completely absent on the moon due to which there is no atmospheric pressure.

Atmospheric pressure is the pressure exerted by the atmosphere on any body.
As there is no pressure, the minimum vapor pressure of the water at ${{0}^{o}}C$ will be equal to the external pressure and its boiling point will decrease considerably.

The temperature at which the vapor pressure of the substance is equal to the external pressure is called the boiling point of a substance.

The water will reach its boiling point and ${{0}^{o}}C$ and it will start boiling.
Therefore, the water will boil at ${{0}^{o}}C$ on the moon.

Hence, the correct option is (C).

Additional Information:
Boiling point of a substance is usually the temperature at which a substance changes its state from liquid to vapour while freezing point is the temperature at which a liquid substance changes its state to solid. Pressure determines the melting point of a substance.

Note:
The boiling point of a substance is directly proportional to the external pressure. The vapor pressure of a substance is the pressure at which it is in equilibrium with its condensed state. The boiling point is attained at a temperature because when volume is constant, pressure is directly proportional to temperature.