The vapour pressure of water is `12.3 kPa` at `300 K`. Calculate vapour pressure of `1` molal solution of a solute in it.

Options

A. `10.08`
B. `12.08`
C. `18.02`
D. `20.10`

Answer

B

Explanation

Solution is 1 molal
`:."Solute"=1mol`
`"Water "1000g=(1000)/(18)mol=55.55mol`
`"Total moles"=56.55`
`"Mole fraction of water"=(55.55)/(56.55)`
`:.p_("solution")=p_("solvent")^(@)xx"mole fraction of water"`
`12.3xx(55.55)/(56.55)=12.08k"pa"`