The vapour pressure of water at `20^(@)` is `17.5 mmHg`. If `18 g` of glucose `(C_(6)H_(12)O_(6))` is added to `178.2 g` of water at `20^(@) C`, the vapour pressure of the resulting solution will be

Options

A. `16.500 mm Hg`
B. `17.325 mm Hg`
C. `17.675 mm Hg`
D. `15.750 mm Hg`

Answer

B

Explanation

`(p^(@)-p_(s))/(p_(s))=(n_(2))/(n_(1))=(W_(2)//M_(2))/(W_(1)//M_(1))`
`(17.5-p_(s))/(p_(s))=(18//180)/(178.2//18)`
or `(17.5)/(p_(s))-1=(1//10)/(9.9)=(1)/(99)`
`(17.5)/(p_(s))=1+(1)/(99)=(100)/(99)`
or`p_(s)=17.5xx(100)/(99)=17.325` mm.