Isotonic solutions must have the same

(A) Solute
(B) Density
(C) Elevation in boiling point
(D) Depression in freezing point

Choose the correct answer from the options given below:

(C) and (D) only

The correct answer is Option (2) → (C) and (D) only

Core Concept:

Isotonic solutions have equal osmotic pressure, which depends on number of solute particles. Since osmotic pressure is a colligative property, it is related to other colligative properties like boiling point elevation and freezing point depression.

Option (A) Solute

Incorrect because isotonic solutions can have different solutes as long as the number of solute particles (effective concentration) remains the same.

Option (B) Density

Incorrect because density depends on mass and volume, not on number of solute particles affecting osmotic pressure.

Option (C) Elevation in boiling point

Correct because boiling point elevation depends on number of solute particles, same as osmotic pressure.

Option (D) Depression in freezing point

Correct because freezing point depression is also directly related to number of solute particles.