Visha took two aqueous solutions, one containing 7.5 g of urea (Molar mass = 60 g/mol) and the other containing 42.75 g of substance Z in 100 g of water, respectively. It was observed that both the solutions froze at the same temperature. Calculate the molar mass of Z.

Answer

`"342 g mol"^(-1)`

Explanation

`DeltaT_(f)=K_(f)xxm." As "DeltaT_(f)` is same for the two solution, their molalities will be equal, i.e.,
`(7.5)/(60)xx(1000)/(100)=(42.75)/(M)xx(1000)/(10) or M=342.`