A gaseous mixture contains oxygen and nitrogen in the ratio of 1:4 by weight. Therefore, the ratio of their number of molecules is

Options

A. `1:4`
B. `7:32`
C. `1:8`
D. `3:16`

Answer

B

Explanation

Let mass of `O_2 = x `
Mass of `N_2 = 4x`
Moles of `O_2 = (x)/(32)`
molecules of `O_2 = (x)/(32) xx 6.02 xx 10^23`
Moles of `N_2 = (4x)/(28) = x/7`
Molecules of `N_2 = x/7 xx 6.02 xx 10^23`
Ratio of molecules ` = (x)/(32) xx 6.02 xx 10^23 , x/7 xx 6.02 xx 10^23`
`1/32 : 1/7`
`7:32`