Q107 / 180 · NEET 2017 · Physics

A gas mixture consists of 2 moles of O2 and 4 moles of Ar at temperature T. Neglecting all vibrational modes, the total internal energy of the system is ( R is universal gas constant)

  • A
    4 RT
  • B
    15 RT
  • C
    9 RT
  • Correct answer
    D
    11 RT

Solution

For a gas having n moles of molecules with each f degrees of freedom at temperature T K, internal energy is U=12nfRT

∴  Total internal energy is

U=n1f12 RT+n2f22 RT

=2×52 RT+4×32RT

=5RT+6RT

U=11RT

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

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