Question

At a constant volume the specific heat of a gas is $0.075$ and its molecular weight is $40$. The gas is :

• A. monoatomic
• B. diatomic
• C. triatomic
• D. none of the above

Answer 1

The correct option is A monoatomic

We know that,
Molar heat capacity at constant volume,

$C_v=$ Specific heat at constant volume $\times$ Mol. wt.

$=0.075\times 40=3.0cal$

$\because C_p-C_v=R$

or $C_p=R+C_v=2+3=5$

Now, $\frac{C_p}{C_v}=\gamma ;\therefore \gamma =\frac{5}{3}=1.66$

This value shows that the gas is monoatomic.

Hence, option $A$ is correct