Question

If a gas is expanded at constant temperature

• A. the pressure decreases
• B. the kinetic energy of the molecules remains the same
• C. the kinetic energy of the molecules decreases
• D. the number of molecules of the gas increases

Answer 1

Answer: (B)

the kinetic energy of the molecules remains the same

Answer 2

Pressure is inversely proportional to volume at constant temperature, hence (a) is correct.
Average kinetic energy of a gas is directly proportional to absolute temperature, hence (b) is correct.
Expansion at constant temperature cannot change the number of molecules, hence (d) is incorrect.