MHT CET Medical202622 April 2026Evening ShiftPhysicsKinetic Theory of GasesActual
The total internal energy of one mole of HCl molecule is (assume the molecule to be non-rigid)
Options
- A3 2 RT
- B7 2 RT
- C5 2 RT
- D9 2 RT
Correct answer
B. 7 2 RT
Step-by-step solution
HCl is a diatomic molecule. For a non-rigid diatomic molecule, the degrees of freedom are: Translational degrees of freedom = 3 Rotational degrees of freedom = 2 Vibrational degrees of freedom = 2 (since each vibrational mode contributes two degrees of freedom, one for kinetic energy and one for potential energy). Total degrees of freedom f = 3 + 2 + 2 = 7 . By the law of equipartition of energy, the internal energy of one mole of a gas is given by U = f 2 RT . Substituting f = 7 , we get U = 7 2 RT . Answer: 7 2 R