Electrochemistry Ques 12

12. Ionic mobility of which of the following alkali metal ions is lowest when aqueous solution of their salts are put under an electric field? [2017]

(a) $K$

(b) $Rb$

(c) $Li$

(d) $Na$

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Answer:

Correct Answer: 12.(c)

Solution:

(c) $Li^{+}$being smallest, has maximum charge density.

$\therefore \quad Li^{+}$is most heavily hydrated among all alkali metal ions. Effective size of $Li^{+}$in aqueous solution is therefore, largest. So, moves slowest under electric field.