Question

if ideal gas expands at constant temperature

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

Hint:

At constant T, \(KE\) depends only on number of moles.

Answer 1

The Correct Option is C

Step 1: Constant temperature ⇒ internal kinetic energy \[ KE = \frac{3}{2} nRT \] remains unchanged.
Step 2: During expansion at same T - molecules do not increase → (B wrong), - pressure falls rather than increases → (D wrong).
Step 3: The only universally true statement is kinetic energy remains same. Hence the incorrect choice asked in options identification is (C).