Arrange the following electrolytes in the increasing order of van't Hoff factor(i) for complete dissociation of solute.

(A) $[Co(NH_3)_6]Cl_3$
(B) $MgCl_2$
(C) $K_4[Fe(CN)6]$
(D) $KCl$

Choose the correct answer from the options given below:

(D), (B), (A), (C)

The correct answer is Option (2) → (D), (B), (A), (C)

For complete dissociation, the van’t Hoff factor (i) equals the total number of ions produced per formula unit.

Let’s find iii for each electrolyte:

• (D) KCl → K⁺ + Cl⁻
  i = 2
• (B) MgCl₂ → Mg²⁺ + 2Cl⁻
  i = 3
• (A) [Co(NH₃)₆]Cl₃ → [Co(NH₃)₆]³⁺ + 3Cl⁻
  i = 4
• (C) K₄[Fe(CN)₆] → 4K⁺ + [Fe(CN)₆]⁴⁻
  i = 5

Increasing order of van’t Hoff factor:

$\text{KCl (2)} < \text{MgCl₂ (3)} < [\text{Co(NH₃)₆]Cl₃ (4)} < \text{K₄[Fe(CN)₆] (5)}$