Question

For a gas if $\gamma = 1.4$, then atomicity, $C_{p}$ and $C_{v}$ of the gas are respectively

• A. Monoatomic, $\frac{5}{2}R,\mspace{6mu}\frac{3}{2}R$
• B. Monoatomic, $\frac{7}{2}R,\mspace{6mu}\frac{5}{2}R$
• C. Diatomic, $\frac{7}{2}R,\mspace{6mu}\frac{5}{2}R$
• D. Triatomic, $\frac{7}{2}R,\mspace{6mu}\frac{5}{2}R$

Answer 1

Answer: (C)

Diatomic, $\frac{7}{2}R,\mspace{6mu}\frac{5}{2}R$

Answer 2

$\gamma = 1 + \frac{2}{f} \Rightarrow 1.4 = 1 + \frac{2}{f} \Rightarrow$Degree of freedom $f = 5$

$\Rightarrow$Degree of freedom of diatomic gas is 5 and it’s

$C_{P} = \frac{7}{2}R$ and $C_{V} = \frac{5}{2}R$