The boiling point of `0.2 mol kg^(-1)` solution of `X` in water is greater than equimolal solution of `Y` in water. Which of the following statements is true in this case?

Options

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

Answer

A

Explanation

Molality of solution X = molality of solution Y
= 0.2 mol/kg
We know that, elevation in the boiling point `(Delta T_(b))` ofa solution is proportional to the molal concentration of the solution i.e.
`Delta T_(prop m` or `Delta T_(b)=K_(b)m`
where, m is the molality of the solution and `K_(b)` is molal boiling point constant or ebullioscopic constant.
`therefore` By elevation in boiling point relation
`Delta T_(b)=iK_(b)m` or `Delta T_(b)prop i`
where, i is van't Hoff factor
Since, `Delta T_(b)` of solution X is greater than `Delta T_(b)` of solution Y.
(Observed colligative property is greater than normal colligative property)
`therefore` i of solution X gt i of solution Y
`therefore` Solution X undergoing dissociation.