For a gas,$R/C_V = 0.67$. What kind of molecules is this gas made of?

If a gas has $f$ degrees of freedom,what is the ratio ${C_p}/{C_v}$?

Column-$I$ represents the type of gas and Column-$II$ represents the ${C_P}$ value for that type of gas. Match them correctly:

Column-$I$	Column-$II$
$(a)$ Monoatomic gas	$(i)$ ${C_P} = \frac{3}{2}R$
$(b)$ Diatomic gas with vibration	$(ii)$ ${C_P} = \frac{5}{2}R$
	$(iii)$ ${C_P} = \frac{7}{2}R$
	$(iv)$ ${C_P} = \frac{9}{2}R$

$A$ mixture of one mole of monoatomic gas and one mole of a diatomic gas (rigid) is kept at room temperature $\left(27^{\circ} C\right)$. The ratio of the specific heat of these gases at constant volume is:

The figure shows the graph of logarithmic reading of pressure and volume for two ideal gases $A$ and $B$ undergoing an adiabatic process. From the figure, it can be concluded that:

At constant volume,the specific heat of a gas is $\frac{3R}{2}$. Then the value of $\gamma$ will be ....