Question

When an ideal diatomic gas is heated at constant pressure then what fraction of heat given is used to increase internal energy of gas ?

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

Answer 1

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

For a diatomic gas we have the degree of freedom as 5.

Thus heat given at constant pressure is given as $n{C}_p\Delta T=n(1+\frac{5}{2})R\Delta T=n\frac{7}{2}R\Delta T$.

The heat given to change the internal energy is $n{C}_v\Delta T=n\frac{5}{2}R\Delta T$.

The fraction of internal energy thus used is $\frac{5}{7}$