An ideal gas at $27^{\circ} \mathrm{C}$ is compressed adiabatically to (8/27) of its original volume. If…

An ideal gas at $27^{\circ} \mathrm{C}$ is compressed adiabatically to (8/27) of its original volume. If ratio of specific heats, $\gamma=5 / 3$ then the rise in temperature of the gas is
  1. $500 \mathrm{~K}$
  2. $125 \mathrm{~K}$
  3. $250 \mathrm{~K}$
  4. $375 \mathrm{~K}$

Solution

For an adiabatic process $\mathrm{TV}^{\gamma-1}=$ constant $\begin{aligned} & \therefore \frac{\mathrm{T}_2}{\mathrm{~T}_1}=\left(\frac{\mathrm{V}_1}{\mathrm{~V}_2}\right)^{\gamma-1}=\left(\frac{27}{8}\right)^{\frac{5}{3}-1}=\left(\frac{27}{8}\right)^{\frac{2}{3}}=\frac{9}{4} \\ & \therefore \mathrm{T}_2=\frac{9}{4} \cdot \mathrm{T}_1=\frac{9}{4} \times 300=675 \mathrm{~K} \\ & \therefore \mathrm{T}_2-\mathrm{T}_1=675-300=375 \mathrm{~K} \end{aligned}$ .

Asked in: MHT CET 2021 (22 Sep Shift 2)

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