Question

A polyatomic gas with six degrees of freedom does 25J of work when it is expanded at constant pressure. The heat given to the gas is:-

• A. 100J
• B. 150J
• C. 200J
• D. 250J

Answer 1

The correct option is A 100J

$$\begin{array}{c}Accorrdingtoquestion.......................\\ Here:\\ freedom\left(f\right)=6^0\\ r=1+\frac{2}{6}=\frac{4}{3}\\ \frac{\Delta w}{\Delta Q}=\frac{\Delta Q-\Delta u}{\Delta Q}=1-\frac{\Delta u}{\Delta Q}=1-\frac{ncu\Delta T}{ncp\Delta T}\\ \Rightarrow 1-\frac{1}{r}=1-\frac{1}{\frac{4}{3}}=\frac{4-3}{4}=\frac{1}{4}\\ \Rightarrow \frac{\Delta w}{\Delta Q}=\frac{1}{4}\\ \therefore \Delta Q=4\times \Delta w=4\times 25j=100j\\ SothecorrectoptionisA.\end{array}$$