Four different electrolyte solutions with the concentrations given below have the same molar conductivity value of $1.29 × 10^{-4}\, S\, m^2\, mol^{-1}$. Arrange them in increasing order of their conductivity values:

(A) 0.1 M
(B) 0.075 M
(C) 0.15 M
(D) 0.05 M

Choose the correct answer from the options given below:

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

The correct answer is Option (4) → (D), (B), (A), (C)

Given:

Molar conductivity (Λₘ) is the same for all four solutions: $Λ_m =1.29 × 10^{-4}\, S\, m^2\, mol^{-1}$

Relation:

Λₘ = κ / c ⇒ Conductivity (κ) = Λₘ × c

Since Λₘ is constant, κ ∝ c (concentration)

∴ The solution with lowest concentration will have lowest conductivity, and the one with highest concentration will have highest conductivity.

Concentrations:

• (D) 0.05 M → lowest
• (B) 0.075 M
• (A) 0.1 M
• (C) 0.15 M → highest

Increasing order of conductivity (κ): (D) < (B) < (A) < (C)