A mixture of ideal gasses `N_(2)` and He are taken in the mass ratio 14:1 respectively. Molar heat capacity of the mixture at constant pressure is

Options

A. `(19R)/6`
B. `(6R)/19`
C. `(13R)/6`
D. `(6R)/13`

Answer

A

Explanation

`(M_(N_(2)))/(M_(H_(2)))=14/1`, `M_(H_(2))=14 m & M_(H_(2))=m`
`C_(p)=(n_(1)CP_(1)+n_(2)CP_(2))/(n_(1)+n_(2))`
` =((14m)/28xx7/2 R+m/4xx5/2 R)/((14m)/28+m/4)=(2xx7/2 R+5/2 R)/3=(19R)/6`