The units of molar conductivity is

The correct answer is Option (2) → S cm² mol⁻¹

Molar conductivity (Λ_m) is the conductivity of a solution divided by its molar concentration. It measures the conducting power of all the ions produced by one mole of the electrolyte:

    \( \displaystyle \Lambda_m=\frac{\kappa}{c} \)

The unit follows from the units of κ and c:

    \( \displaystyle \kappa:\ \mathrm{S\,cm^{-1}}\quad c:\ \mathrm{mol\,cm^{-3}} \)

    \( \displaystyle \Lambda_m=\frac{\mathrm{S\,cm^{-1}}}{\mathrm{mol\,cm^{-3}}}=\mathrm{S\,cm^{-1}\,cm^{3}\,mol^{-1}}=\mathrm{S\,cm^{2}\,mol^{-1}} \)

In SI units it is S m² mol⁻¹ (1 S m² mol⁻¹ = 10⁴ S cm² mol⁻¹).

NCERT (2026-27 edition):
Measurement of the Conductivity of Ionic Solutions – “… It, therefore, becomes necessary to define a physically more meaningful quantity called molar conductivity denoted by the symbol Λ_m (Greek, lambda). It is related to the conductivity of the solution by the equation:

    \( \displaystyle \text{Molar conductivity}=\Lambda_m=\frac{\kappa}{c} \)

… If we use S cm^–1 as the units for κ and mol cm^–3, the units of concentration, then the units for Λ_m are S cm² mol^–1.”

Note: The same/similar question has been asked in different years by NTA as per the details given below: