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

(a) 2/5

(b) 3/5

(c) 3/5

(d)5/7

Ans: (d)

Sol: Fraction , $\large f = \frac{\Delta U}{\Delta Q} $

$\large f = \frac{n C_V \Delta T}{n C_P \Delta T} $

$\large f = \frac{ C_V }{C_P} = \frac{1}{\gamma} $

$\large f = \frac{5}{7} $