The molar specific heat at constant pressure of an ideal gas is `(7//2 R)`. The ratio of specific heat at constant pressure to that at constant volume is

Options

A. `7//5`
B. `8//7`
C. `5//7`
D. `9//7`

Answer

A

Explanation

We have given molar specific heat at constant pressure
`C_(P) = 7/2 R`
We know `C_(p)-C_(v)=R`
`implies C_(V)=C_(p)-R=7/2R-R=5/2R`
Hence, required ratio is
`gamma=(C_p)/(C_V) = ((7//2)R)/((5//2)R) = 7/5` .