A solution containing 0.1 g of a non-volatile organic substance P (molecular mass 100) in 100 g of benzene raises the boiling point of benzene by `0.2^@C,` while a solution containing 0.1 gof another non-volatile subistance Q in the same amount of benzene raises the boiling point of benzene by `0.4^@C`. What is the ratio of molecular masses of P and Q?

Options

A. `1:2`
B. `2:1`
C. `1:4`
D. `4:1`

Answer

B

Explanation

`((Delta T)_(P))/((Delta T)_(Q))= (K_(b) xx ((w_(B) xx 1000)/(m_(B) xx w_(A)))_(P))/(K_(b)xx ((w_(B) xx 1000)/(m_(B) xx w_(A)))_(Q))`
`(0.2)/(0.4)= (((0.1xx 1000)/(100 xx 100)))/(((0.1xx 1000)/(100 xx m_(B)))_(Q)), (1)/(2) ((m_(B))_(Q))/(100)`
`m_(B)= 50 therefore (m_(B))_(P), (m_(B))_(Q)= 100:50 =2:1`