JEE Main · 2019 · 10 Apr 2019 · Shift 2 · Redox Reactions and Electrochemistry

Both salts are strong electrolytes, so each obeys Kohlrausch's square-root law ${\Lambda }_m={\Lambda }_m^0-A\sqrt{C}$ and plots as a straight line sloping gently down as $\sqrt{C}$ increases, meeting the axis at its limiting value ${\Lambda }_m^0$. Because potassium ions are less heavily hydrated and so more mobile than sodium ions, $\mathrm{KCl}$ sits above $\mathrm{NaCl}$ throughout. The correct graph is the pair of near-parallel falling lines with $\mathrm{KCl}$ lying above $\mathrm{NaCl}$.