Question

For the diatomic ideal gas in the closed system which of the following plots does not correctly describe the relation between various thermodynamic quantities ?

• A.
• B.
• C. .
• D. .

Answer 1

The correct option is B

We know value of $C_v$ is independent of volume (V) and depends in T i.e.at a constant temperature for any given value of V we have same value of $C_v$. So the graph between $C_v$ and V will be parallel to X-axis.
Similarly the value of $C_p$ is independent of P and depends on T i.e. at constant temperature for any given value of P we have same value of $C_p$.So, we can say graph b is incorrect.
Also at higher temperatures, the rotational degree of freedom becomes active. So, with the increase in temperature the internal energy and heat capacity increases.