A sample of gas is contained in a tube under a mercury plug. which tube represents the gas after the sample is cooled at constant pressure?

Option A. The volume of gas will reduce.

Explanation:

The problem can be analyzed by using Charles' law which states that the volume of an ideal gas is directly proportional to the absolute temperature at constant pressure. Mathematically we have:

Initial volume/initial temperature = final volume/final temperature.

Therefore, if the sample is cooled at constant pressure, that means the temperature of the system is reduced. If the temperature is reduced, then the volume of gas will also reduce and vice versa. Therefore for the given problem, the tube that represents the gas after the sample is cooled at constant pressure is the tube in option 'A' that shows decrease in the volume of gas.