When two moles of an ideal gas $\left({\mathrm{C}}_{\mathrm{p},\mathrm{m}.}=\frac{5}{2}\mathrm{R}\right)$ heated from 300 K to 600 K at constant pressure, the change in entropy of gas (68) is :

Change in entropy can be given as,

$\mathrm{\Delta }S=n{C}_p$ in $\frac{T_2}{T_1}$  (for constant pressure)

We have given that,

$\begin{array}{l}\mathrm{n}=2\text{ moles }\\ {\mathrm{C}}_{\mathrm{P}}=\frac{5}{2}\mathrm{R}\\ {\mathrm{T}}_2=600\mathrm{K}\\ {\mathrm{T}}_1=300\mathrm{K}\end{array}$

So,

$\begin{array}{l}\mathrm{\Delta S}=2\times \frac{5}{2}\mathrm{R}\times \ln \frac{600}{300}\\ \mathrm{\Delta S}=5\mathrm{R} \ln 2\end{array}$