Q32 / 180 · JIPMER 2019 · Chemistry
What is the value of $\gamma$ for mono atomic gas (ideal gas)?
- A$\frac{7}{5}$
- B$\frac{4}{3}$
- C$\frac{5}{2}$
- Correct answerDNone of these
Solution
Key Idea $\gamma=\mathrm{C}_{\mathrm{P}} / \mathrm{C}_{\mathrm{V}}$ where, $\mathrm{C}_{\mathrm{P}}$ and $\mathrm{C}_{\mathrm{v}}$ are heat capacities at constant pressure and volume, respectively.
For monoatomic gas, $\mathrm{C}_{\mathrm{P}}=5 \mathrm{cal}, \mathrm{C}_{\mathrm{V}}=3 \mathrm{cal}$
$\gamma=\frac{\mathrm{C}_{\mathrm{P}}}{\mathrm{C}_{\mathrm{V}}}=\frac{5}{3}=1.67$
For diatomic gas, $\mathrm{C}_{\mathrm{P}}=7 \mathrm{cal}, \mathrm{C}_{\mathrm{V}}=5 \mathrm{cal}$
$_{\mathrm{V}}=6 \mathrm{cal}$
$\gamma=\frac{C_P}{C_V}=\frac{8}{6}=1.33$
Hence, the correct answer is option: 'D'.