Calculate the mole fraction of solute in a dilute aqueous solution from which ice begins to separate out at `-46^(@)C`. (`K_(f)` of `H_(2)O` =`1.86 K m^(-1)`)

Explanation

`DeltaT_(f)=K_(f) xx m rArr m=(DeltaT_(f))/K_(f)=(0-(0-0.46))/1.86 = 0.46/1.86=0.247 m`
Use the relation,
`m=(n_(2)xx1000)/(n_(1)xxMw_(1))`
`:.n_(2)/n_(1)=chi_(2)=(m xx Mw_(1))/1000`
=`(0.247 xx 18)/1000`
`=0.004`