KVPY SX SB Exam 2018 Question Paper

Question : 25 of 120

Marks: +1, -0

A thermally insulated rigid container of one litre volume contains a diatomic ideal gas at room temperature. A small paddle installed inside the container is rotated from the outside such that the pressure rises by 10

^{5}

Pa. The change in internal energy is close to

0 J
67 J
150 J
250 J

Validate

Solution:

∆U = n C_v(T_2-T_1)

={nR}/{γ-1}[{P_2V}/{nR}-{P_1V}/{nR}]

={(P_2-P_1)V}/{γ-1}

= {(2×10^5-1×10^5)×10^{-3}}/{7/5-1}

5/2×100=250J

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