Question

When an ideal diatomic gas is heated at constant pressure, the fraction of the heat supplied which increases the internal energy of the gas is:

• A. $\frac{2}{5}$
• B. $\frac{3}{5}$
• C. $\frac{3}{7}$
• D. $\frac{5}{7}$

Answer 1

Answer: (D)

$\frac{5}{7}$

Fraction of heat $\left(f\right)=\frac{△U}{△Q}=\frac{n{C}_V△T}{n{C}_P△T}=\frac{C_V}{C_P}=\frac{1}{\gamma }$

Now

$f=\frac{1}{\gamma }=\frac{5}{7}$ (for a diatomic gas $\gamma =\frac{7}{5}$)