Question

If a gas expands at constant temperature:

• A. the pressure decreases
• B. the kinetic energy of the molecules remains the same
• C. the $KE$ of the molecules decrease
• D. the number of molecules of the gas increase

Answer 1

Answer: (A), (B)

The correct options are
A the pressure decreases
B the kinetic energy of the molecules remains the same

At constant temperature, the kinetic energy of the molecules remains the same.
And according to $PV=nRT$, as volume increases, pressure decreases.