The unit of molar conductivity is

$S\, cm^2\, mol^{-1}$

The correct answer is Option (4) → $S\, cm^2\, mol^{-1}$

Molar conductivity ($\Lambda_m$) is defined as the conducting power of all the ions produced by dissolving one mole of an electrolyte in solution. It is mathematically expressed as:

$\Lambda_m = \frac{\kappa}{C}$

Where:

• $\kappa$ (Kappa): Specific conductance (Conductivity). Its units are $S\text{ cm}^{-1}$ (or $\Omega^{-1}\text{ cm}^{-1}$).
• $C$: Molar concentration. Its units are $\text{mol L}^{-1}$. In the context of SI/CGS units for conductivity, concentration is often expressed as $\text{mol cm}^{-3}$.

Unit Calculation:

$\text{Unit of } \Lambda_m = \frac{S\text{ cm}^{-1}}{\text{mol cm}^{-3}}$

$\text{Unit of } \Lambda_m = S\text{ cm}^{-1} \times \text{cm}^3 \times \text{mol}^{-1}$

$\text{Unit of } \Lambda_m = S\text{ cm}^2\text{ mol}^{-1}$