Question

Sixty percent of given sample of oxygen gas when raised to a high temperature dissociates into atoms. Ratio of its initial heat capacity (at constant volume) to its final heat capacity (at constant volume) will be

• A. $\frac{6}{7}$
• B. $\frac{25}{26}$
• C. $\frac{10}{7}$
• D. $\frac{25}{27}$

Answer 1

The correct option is C $\frac{10}{7}$

Initial $C_v=\frac{5}{2}R$
When it dissociates,
$f_{av}=\frac{n_1{f}_1+n_2{f}_2}{n_1+n_2}=\frac{1.2\times 3+0.4\times 5}{1.2+0.4}=\frac{7}{2}\{f_{av}=averagedegreesoffreedom\}$
$\therefore Final{C}_v=\frac{favR}{2}=\frac{7}{4}R\therefore \frac{initial{C}_v}{final{C}_v}=\frac{10}{7}$