Medium MCQ +4 / -1 PYQ · JEE Mains 2025

Correct order of limiting molar conductivity for cations in water at 298 K is :

A $\mathrm{H}^{+}>\mathrm{Na}^{+}>\mathrm{K}^{+}>\mathrm{Ca}^{2+}>\mathrm{Mg}^{2+}$
B $\mathrm{H}^{+}>\mathrm{Ca}^{2+}>\mathrm{Mg}^{2+}>\mathrm{K}^{+}>\mathrm{Na}^{+}$ Correct answer
C $\mathrm{Mg}^{2+}>\mathrm{H}^{+}>\mathrm{Ca}^{2+}>\mathrm{K}^{+}>\mathrm{Na}^{+}$
D $\mathrm{H}^{+}>\mathrm{Na}^{+}>\mathrm{Ca}^{2+}>\mathrm{Mg}^{2+}>\mathrm{K}^{+}$

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}{\text{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.

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Subject: Chemistry · Chapter: Electrochemistry · Topic: Electrochemical Cells

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Correct order of limiting molar conductivity for cations in water at 298 K is :

Solution

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