Which of the following graph correctly represents the variation of molar conductance `(Delta_m)` with dilution for a strong electrolyte ?

Options

A.
B.
C.
D.

Answer

To solve the question regarding the variation of molar conductance (Δ_m) with dilution for a strong electrolyte, we will follow these steps:

### Step 1: Understand the Concept of Molar Conductance
Molar conductance (Δ_m) is a measure of the ability of an electrolyte solution to conduct electricity. It depends on the concentration of the electrolyte in solution.

### Step 2: Apply the Debye-Hückel-Onsager Equation
The relationship between molar conductance (Δ_m), molar conductance at infinite dilution (Δ_m0), and concentration (C) is given by the Debye-Hückel-Onsager equation:
\[ Δ_m = Δ_m0 - b \cdot v \cdot C \]
Where:
- Δ_m = Molar conductance at concentration C
- Δ_m0 = Molar conductance at infinite dilution
- b = Debye constant
- v = Valency of the electrolyte
- C = Concentration of the electrolyte

### Step 3: Analyze the Effect of Dilution
When a strong electrolyte is diluted:
- The concentration (C) decreases.
- According to the equation, as C decreases, the term \(b \cdot v \cdot C\) also decreases.
- Therefore, Δ_m increases and approaches Δ_m0 as the solution is diluted.

### Step 4: Determine the Graphical Representation
- As the concentration decreases, Δ_m increases and approaches a maximum value (Δ_m0).
- The correct graph should show an increase in molar conductance with dilution, reaching a plateau at Δ_m0.

### Step 5: Evaluate the Options
- Option 1: Shows a decrease in Δ_m with dilution (incorrect).
- Option 2: Shows an increase in Δ_m with dilution, reaching Δ_m0 (correct).
- Option 3: Shows a decrease in Δ_m with dilution (incorrect).
- Option 4: Shows an increase but does not reach Δ_m0 (incorrect).

### Conclusion
The correct option that represents the variation of molar conductance with dilution for a strong electrolyte is **Option 2**.

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