Which one of the following is NOT a correct expression for an ideal gas? $\left[\mathrm{C}_{\mathrm{p}}=\right.$ Molar specific heat of a gas at constant pressure, $\mathrm{C}_{\mathrm{V}}=$ Molar specific heat of a gas at constant volume, $\gamma=$ Ratio of two specific heats of a gas, $\mathrm{R}=$ Universal gas constant]

• Correct answer
  A

  $\mathrm{C}_{\mathrm{v}}=\mathrm{C}_{\mathrm{p}}+\mathrm{R}$
• B

  $\mathrm{R}=\mathrm{C}_{\mathrm{V}}(\gamma-1)$
• C

  $\frac{\mathrm{C}_{\mathrm{v}}}{\mathrm{C}_{\mathrm{p}}}=\frac{1}{\gamma}$
• D

  $\mathrm{R}=\frac{\mathrm{C}_{\mathrm{p}}(\gamma-1)}{\gamma}$

Hence, the correct answer is option: 'A'.