Question

If a gas is allowed to expand at constant temperature then which of the following is true?

• A. The kinetic energy of the gas molecules decreases
• B. The kinetic energy of the gas molecules increases
• C. The kinetic energy of the gas molecules remains the same
• D. Cannot be predicted

Answer 1

Answer: (C)

The kinetic energy of the gas molecules remains the same

Kinetic energy $=\frac{3}{2}KT$ for a mole of gas.

When the same moles of gas is expanded at a constant temperature, then the kinetic energy of the molecules remain the same.

Thus, $\text{K.E}\propto T$

At constant temperature, kinetic energy is constant.

Hence, option C is correct.