Question

$Q$ cal of heat is required to raise the temperature of 1 mole of a monatomic gas from $20^{\circ }C$ to $30^{\circ }C$ at constant pressure. The amount of heat required to raise the temperature of 1 mole of diatomic gas from $20^{\circ }C$ to $25^{\circ }C$ at constant pressure is:

• A. $Q$
• B. $\frac{3}{2}Q$
• C. $\frac{5}{6}Q$
• D. $\frac{7}{10}Q$

Answer 1

Answer: (D)

$Q=n{C}_P\Delta T=1\times \frac{5}{2}R\times 10=25R$
$Q^{\prime }=1\times \frac{7}{2}R\times 5=\frac{35}{2}R$
$\frac{Q^{\prime }}{Q}=\frac{35}{50}=\frac{7}{10}$
$\Rightarrow Q^{\prime }=\frac{7}{10}Q$