Question

1.00 gm of a non-electrolyte solute dissolved in 50 gm of benzene lowered the freezing point of benzene by 0.40 K. `K_(f)` for benzene is 5.12 kg `mol^(-1)`. Molecular mass of the solute will be
A. `256 g mol^(-1)`
B. `2.56 g mol^(-1)`
C. `512xx10^(3)g mol^(-1)`
D. `2.56xx10^(4)g mol^(-1)`

Answer 1

Correct Answer - A
By using, `m=(K_(f)xx1000xx w)/(Delta T_(f)xx W_("Solvent")(gm))=(5.12xx1000xx1)/(0.40xx50)`
= 256 gm/mol
Hence, molecular mass of the solute `= 256 gm mol^(-1)`