Question

The vapor pressure of a dry gas is:
(a) less than that of a wet gas
(b) greater than that of a gas.
(c) equal to that of a wet gas
(d) double than that of a wet gas

Answer 1

Hint First you should know about the vapor pressure of the wet gas and from that you can easily, calculate the vapor pressure of the dry gas and come to know whether it is lesser, greater or equal to the vapor pressure of the wet gas. Now solve it.

Complete step by step answer:
First of , let’s discuss the vapor pressure. By the term vapor pressure we simply mean the pressure which is exerted by the vapor and the vapor pressure of the liquid increases as the temperature increases.
Now considering the statement;
The vapor pressure of a wet gas is always the vapor pressure of the dry gas and the aqueous tension ( i.e. the partial pressure of the water vapors which are present in the wet gas).
In other words;
Wet gas pressure= dry gas pressure ie aqueous tension
Then , the vapor pressure of dry gas is as;
Dry gas pressure= wet gas pressure- aqueous tension
From this it is clear that the vapor pressure of the dry gas is always less than the vapor pressure of the wet gas.

Hence, option (a) is correct.

Note: It may also be defined as the capacity of the material to change its state from solid or liquid phase to the gaseous phase or the vapor phase. The temperature at which the vapor pressure of the liquid becomes equal to the pressure which is exerted by the surroundings is called the boiling point of the liquid.