JEE Main 2025 — Electrochemistry Question with Solution

The limiting molar conductivities of ions are important in determining how well they conduct electricity in solution. Here are the values for some common cations at 298 K:

H⁺: 349.8 S cm² mol⁻¹

Na⁺: 50.11 S cm² mol⁻¹

K⁺: 73.52 S cm² mol⁻¹

Ca²⁺: 119 S cm² mol⁻¹

Mg²⁺: 106.12 S cm² mol⁻¹

Based on these values, the correct order of limiting molar conductivity for these cations is:

${\stackrel{\oplus }{H}}^{+}>{\text{Ca}}^{2+}>{\text{Mg}}^{2+}>{\text{K}}^{+}>{\text{Na}}^{+}$

This order reflects the decreasing ability of each ion to conduct electricity in water under the given conditions.