$N$ moles of diatomic gas in a cylinder is at a temperature $T$. Heat is supplied to the cylinder such that the temperature remains constant but $n$ moles of the diatomic gas get converted into monoatomic gas. The change in the total kinetic energy of the gas is

• A

  $0$
• B

  $\frac{5}{2}nRT$
• C

  $\frac{3}{2}nRT$
• Correct answer
  D

  $\frac{1}{2}nRT$

Hence, the correct answer is option: 'D'.