138 g of ethyl alcohol is mixed with 72 g of water. The ratio of mole fraction of alcohol to water is

Options

A. `3:4`
B. `1:2`
C. `1:4`
D. `1:1`

Answer

(a)

Explanation

Weight of ethyl alcohol = 138g
Weight of water = 72 g
No. of moles = `(Weight)/("Molecular weight")`
Number of moles of ethyl alcohol` ((1)) = [n_(1)= (138)/(46)=3]`
Number of moles of water `(H_(2)O) (n_(2)) =[ n_(2)=(72)/(18)=4]`
Mole fraction of `C_(2)H_(5)OH (x_(1)) = (n_(1))/(n_(1))+(n_(2)) = (3)/(3+4)=(3)/(7)`
Mole fraction of` H_(2)O (x_(2))` = `(n_(2))/(n_(1)+n_(2)) = (4)/(3+4) = (4)/(7)`
there Ratio of mole fractions `((x_(1))/(x_(3)))= (3/7)/(4/7)=(3)/(4)`
`therefore x_(1): x_(2)= 3:4`