Question

The boiling point of $0.2\, mol\, kg^{-1}$ solution of X in water is greater than equimolal solution of Y in water. Which one of the following statements is true in this case ?

• A. Molecular mass of X is less than the molecular mass of Y
• B. X is undergoing dissociation in water while X undergoes no change.
• C. X is undergoing dissociation in water
• D. Molecular mass of X is greater then the molecular mass of Y.

Answer 1

Answer: (C)

$(\Delta T_b)_x > ( \Delta T_b)_y $
same solvent so, $K_b $ is same
m is same (given)
$i_x . k_b . m > i_y . k_b .m \; \Rightarrow \; i_X > i_y$
so, x is undergoing dissociation in water.