Mass of sugar in 5% (by mass) solution means 5gin 100g of solvent (water)

Molar mass of sugar`=342 " g mol"^(-1)`

Molality of sugar solution `=(5xx1000)/(342xx100)=0.146`

`therfore DeltaT_(f)` for sugar solution `=273.15-271=2.15^(@)`

`Delta T_(f)=K_(f)xxm`

`Delta T_(f)=K_(f)xx0.146 implies K_(f)=2.15//0.146`

Molality of glucose solution

`=(5)/(180)xx(1000)/(100)=0.278`

(Molar mass of glucose`=180 " g mol"^(-1))`

`Delta T_(f)=K_(f)xxm=(2.15)/(0.146)xx0.278=4.09^(@)`

`therefore` Freezing point of glucose solution

`=273.15-4.09=269.06 K`.