Question

Assertion :The mobility of $N{a}^{\oplus }$ is lower than that of $K^{\oplus }$ ion. Reason: The ionic mobility depends upon the effective radius of the ion.

• A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
• B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
• C. Assertion is correct but Reason is incorrect
• D. Assertion is incorrect but Reason is correct

Answer 1

The correct option is A Both Assertion and Reason are correct and Reason is the correct explanation for Assertion

In an aqueous medium, the mobilities of cations depend on :
(i) Charge density [(ionic charge/ionic size) ratio]
(ii) Extent of hydration which decides the effective radius.

Decreasing order of mobility of cations of first group are :

$C{s}^{\oplus }>R{b}^{\oplus }>K^{\oplus }>N{a}^{\oplus }>L{i}^{\oplus }$