What is the unit of molar conductance?

S cm² mol^-1

The correct answer is option 1. S cm² mol^-1.

Molar conductance (\(\Lambda_m\)) is a measure of the ability of a solution of an electrolyte to carry an electric current. It is defined as the conductance of a solution containing one mole of the electrolyte in a volume of one liter, with electrodes placed one centimeter apart.

The unit of molar conductance is Siemens per centimeter squared per mole (\(S \, cm^2 \, mol^{-1}\)). This unit indicates the conductance of the solution normalized to the concentration of the electrolyte.

Molar conductance depends on the concentration of the electrolyte in solution. For strong electrolytes, molar conductance generally decreases with increasing concentration due to the increased ion-ion interactions at higher concentrations. In contrast, for weak electrolytes, molar conductance tends to increase with dilution as more ions are generated due to ionization.

Experimentally, molar conductance is often determined by measuring the conductance of a solution at various concentrations and then plotting the conductance against the square root of concentration (\(c\sqrt{c}\)). This plot typically yields a straight line for strong electrolytes, in accordance with Kohlrausch's Law of Independent Migration of Ions.