Explain the effect of change in concentration on the conductivity of a solution.

(N/A) Both conductivity $(k)$ and molar conductivity $(\Lambda_{m})$ change with the concentration of the electrolyte.
Conductivity $(k)$ always decreases with a decrease in concentration (dilution),for both weak and strong electrolytes.
This is because the number of ions per unit volume that carry the current in the solution decreases upon dilution.
Conductivity is defined as the conductance of one unit volume of solution kept between two platinum electrodes with unit area of cross-section and unit length. If $G$ is the conductance,$A$ is the cross-sectional area,and $l$ is the distance between electrodes,then $G = k \left( \frac{A}{l} \right)$. For $A = 1$ and $l = 1$,$G = k$.
Molar conductivity $(\Lambda_{m})$ is the conductance of the volume $V$ of solution containing one mole of electrolyte kept between two electrodes. It is related to conductivity by the equation $\Lambda_{m} = k V$. As concentration decreases,$V$ increases,which leads to an increase in molar conductivity.