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

Options

A. `2//5`
B. `3//5`
C. `3//7`
D. `5//7`

Explanation

Heat use in increasing the internal energy `= C _(v) Delta H.` Heat absorbed at constant pressure to increase the temparature by `Delta T = C _(p) Delta T`
Hence , Fraction of heat used in increasing the internal energy `phi = ( C _(V) Delta T)/( C _(P) DeltaT) = ( C _(V))/( C _(P))`
For a diatomic gas, `C _(V,m) = (5//2) R and C _(p,m) = (7//2) ` R Hence `phi = ( ( 5//2)R)/( ( 7//2) R) = ( 5)/(7)`