The variation of \(\Lambda _m\) with \(\sqrt{c}\) for a strong electrolyte is shown in the graph. Identify the correct representation for the same

The correct answer is option 4.

For strong electrolyte molar conductivity increases with dilution due to decrease in ion- ion force of attraction. As strong electrolytes are mostly in ionized state, no abrupt change in the number of ions with dilution. Thus, \(\Lambda _m\) increases slowly with dilution. In concentrated solution there will be a strong attraction between ions which slows down the movement of ion. On dilution of strong electrolyte, distance between the ions increases which results in decrease in ion-ion attraction. So, there will be overall increase in molar conductance of the solution.

Variation in molar conductivity of strong electrolyte due to ion-ion interaction is given by an empirical relation proposed by kohlrausch.

\(\Lambda _m = \Lambda_m^0 – A\sqrt{C}\)

\(\Lambda _m\) is the molar conductivity

\(\Lambda _m^0\) is Limiting molar conductivity

\(C\) is the concentration of electrolyte

\(A\) is constant for a given solvent and temperature

\(\Lambda _m = \Lambda_m^0 – A\sqrt{C}\)

This equation is in the form of straight line equation,

\(y = c + mx\)

So, the plot of \(\Lambda _m\) vs \(\sqrt{C}\)