Question

Which one of the following ions has highest limiting molar conductivity ?

• A. $Na^+$
• B. $Mg^{2+}$
• C. $K^+$
• D. $Ca^{2+}$

Answer 1

Answer: (D)

$Ca^{2+}$

Answer 2

$\begin{matrix}Ion&Na^{+}&K^{+}&Mg^{+}&Ca^{+}\\\ \Lambda^{\circ}_{m}&50.70&73.50&106.0&119.0\end{matrix}$ $(S\,cm^2\,mol^{-1})$ The size of hydrated $Na^+$ ion is largest and that of $Ca^{2+}$ is the smallest. Hence they follow the above order.