A and B are ideal gases. The molecular weights of A and B are in the ratio of `1 : 4`. The pressure of a gas mixture containing equal weights of A and B is P atm. What is the partial pressure (in atm.) of B in the mixture

Options

A. `P//5`
B. `P//2`
C. `P//2.5`
D. `3P//4`

Answer

A

Explanation

Let `M_(A) = a " and " M_(B) = 4a`
`w_(A) = w_(B) = m` (say)
`x_(B) = (m//4a)/(m//4a + m//a) = (1)/(5)`
`P_(B) = x_(B) xx P_("total") = P//5`