Question

When an ideal diaatomic gas is heated at constant pressure, the fraction of the heat energy 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

The correct option is D $\frac{5}{7}$

$Q_P=n{C}_{p}dT$
$\Delta U=n{C}_{v}dT$
The fraction of heat supplied that increases the internal energy is
$\frac{\Delta U}{Q_p}=\frac{n{C}_{v}dT}{n{C}_{p}dT}=\frac{C_v}{C_p}=\frac{\frac{5}{2}R}{\frac{7}{2}R}=\frac{5}{7}$