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JEE Main levelSingle correct optionDifficulty 2 of 3td189

One mole of a monatomic ideal gas is heated from $300 K$ to $400 K$ in a rigid vessel. Taking $R = 8.314 J mo l^{- 1} K^{- 1}$ , the enthalpy change $Δ H$ is nearest to

A $1.25 kJ$
B $2.08 kJ$
C $0.83 kJ$
D $3.12 kJ$

Answer: B

For an ideal gas

Δ H = n C_{P} Δ T

for any process, because

H

depends only on

T

. So

Δ H = 1 \times 2.5 \times 8.314 \times 100 = 2078 J = 2.08 kJ

. The heat absorbed at constant volume is only

1.25 kJ

.

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