Which solution will have the highest boiling point?

The correct answer is Option (1) → 1 M \(BaCl_2\) solution

Elevation of boiling point is a colligative property: it depends on the number of solute particles, ΔT_b = iK_bm. At the same concentration, the solute giving the most particles (largest van’t Hoff factor i) has the highest boiling point:

• \( \ce{BaCl2} \) → \( \ce{Ba^{2+}} \) + \( \ce{2Cl^{-}} \): i = 3

• NaCl → \( \ce{Na^{+}} \) + \( \ce{Cl^{-}} \): i = 2

• Glucose and urea do not dissociate: i = 1

NCERT (2026-27 edition):
Colligative Properties and Determination of Molar Mass – “… All these properties depend on the number of solute particles irrespective of their nature relative to the total number of particles present in the solution. Such properties are called colligative properties (colligative: from Latin: co means together, ligare means to bind).”