If one mole of an ideal gas $\left(\gamma=\frac{5}{3}\right)$ is mixed with one mole of a diatomic gas…

If one mole of an ideal gas $\left(\gamma=\frac{5}{3}\right)$ is mixed with one mole of a diatomic gas $\left(\gamma=\frac{7}{5}\right)$. The value of $\gamma$ for the mixture is
  1. $1.50$
  2. $1.53$
  3. $3.07$
  4. $1.40$

Solution

As we know, $C_v=\frac{3}{5} R T ; C_p=\frac{5 R T}{2}$ for monoatomic gas; $C_v=\frac{5}{2} R T ; C_p=\frac{7}{2} R T$ for diatomic gas Thus, for mixture of 1 mole each, $C_v=\frac{\frac{3}{2} R T+\frac{5}{2} R T}{2}$ and $C_p=\frac{\frac{5}{2} R T+\frac{7}{2} R T}{2}=3 R T$ Therefore, $\frac{C_v}{C_p}=\frac{3 R T}{2 R T}=1.5$

Asked in: MHT CET 2022 (07 Aug Shift 2)

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