Question

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

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

Answer 1

Answer: (D)

$\left(\left(ΔT\right)_{b}\right)_{x}>\left(\left(ΔT\right)_{b}\right)_{y}$
same solvent so, $K_{b}$ is same
$m$ is same (given)
$i_{x}\cdot k_{b}\cdot m>i_{y}\cdot k_{b}\cdot m\Rightarrow i_{x}>i_{y}$
so, $x$ is undergoing dissociation in water.