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`

Answer

B

Explanation

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