JEE Mains 2020 Model Paper 1 New Pattern

Total number of degrees of freedom in a thermo dynamical system = Number of degrees of freedom associated per molecule = Number of molecules,
As given molecules are of hydrogen,
∴ Volume occupied by 1 mole = 1 mole of the gas at NTP = 22400mL = 22400cc
Any ideal gas has a molar volume of 22400 mL (cc) at NTP.
∴ Number of molecules in 1 cc of hydrogen =

6.023×1023

22400

= 2.688 × 1019
H2 is diatomic gas, having a total of 5 degrees of freedom (3 translational + 2 rotational)
∴ Total degrees of freedom possessed by all the molecules = 5 × 2.688 × 1019 = 1.344 × 1020