For solutes showing association, the value of van*t Hoff factor (i) is: 

CONCEPT:

Van't Hoff Factor (i)

• The van't Hoff factor (i) is a measure of the effect of a solute on colligative properties (such as boiling point elevation, freezing point depression, vapor pressure lowering, and osmotic pressure).
• It represents the number of particles into which a solute dissociates or associates in solution.
• For solutes that associate, the particles combine together to form larger particles, reducing the total number of particles in solution.

EXPLANATION:

• For solutes showing association:
  • The molecules of the solute combine or aggregate to form larger units.
  • As a result, the number of particles in solution decreases, leading to a van't Hoff factor (i) that is less than 1.
  • For example, in cases of dimerization or trimerization, two or more solute particles combine to form a single particle.
• In contrast, solutes showing dissociation (e.g., ionic compounds) result in an increase in the number of particles, leading to a van't Hoff factor (i) that is greater than 1.

Therefore, for solutes showing association, the value of the van't Hoff factor (i) is less than 1, and the correct answer is Option 1.