Density of dry air `(` only `N_(2)` and `O_(2))` is `1.24g` `litre^(-1)` at `760 m m` and `300 K`. Find the partial pressure of `N_(2)` gas in aire. ( Take `R=(1)/(12)` litre litre atm`//`mol K, mol. Wt. of `N_(2) =28)`

Options

A. `0.25`
B. `0.35`
C. `0.5`
D. `0.75`

Answer

1

Explanation

`d_(mix)=(PM_(mix))/(RT)`
`1.2(1atmxxM_(mix))/((1)/(12)xx300)`
`M_(mix)=1.24xx25=21`
`M_(mix)=X_(O_(2))xxM_(O_(2))+(1-X_(O_(2)))M_(N_(2))`
`31=x xx32+(1-x)28`
`x=(3)/(4)`
`:." "P_(O_(2))=x_(O_(2))xxP_(T)=(3)/(4)atm`
`P_(N_(2))=(1)/(4)ATM=0.25atm`