MHT CET · Chemistry · Solutions

Which one of the following aqueous solutions will exhibit the highest boiling point?

A $0.01 M {KNO}_{3}$
B $0.015 M$ urea
C $0.015 M$ glucose
D $0.01 M$ ${Na}_{2} {SO}_{4}$

Verified Solution

Answer & Solution

Correct Answer

(D) $0.01 M$ ${Na}_{2} {SO}_{4}$

Step-by-step Solution

Detailed explanation

Elevation in boiling point is a colligative property which depends upon the number of solute particles.
Greater the number of solute particles in a solution, higher the extent of elevation in boiling point.

{Na}_{2} {SO}_{4} ⟶ 2 {Na}^{+} + {SO}_{4}^{2 -}

. On complete dissociation,

i = 3

{(Δ T_{b})}_{{KNO}_{3}} = i K_{b} \cdot m (i = 2)

{(Δ T_{b})}_{urea} = i K_{b} \cdot m (i = 1)

{(Δ T_{b})}_{glucose} = i K_{b} \cdot m (i = 1)

{(Δ T_{b})}_{{Na}_{2} {SO}_{4}} = i K_{b} \cdot m (i = 3)

The Van't Hoff factoris the highest for

{Na}_{2} {SO}_{4}

andwill exhibit the highest boiling point

Apply the relevant identity from the chapter and substitute the values established in the previous step, keeping the original constraint in view.

Use the simplified expression to isolate the unknown, then plug the result back into the question setup to confirm the working is internally consistent.

Cross-check against a boundary or limiting case. Both the dimensional balance and the qualitative behaviour at the extreme should agree with the candidate answer.

Combine the steps above to identify the correct option. The remaining choices each fail at least one of the consistency, dimensional, or boundary checks.

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