Question

Among $K^+, Li^+, Rb^+, Cs^+$, the number of cation(s) having ionic radii more than $Na^+$ is/are _____.

Answer 1

Correct Answer: 3

To determine how many of the cations $K^+$, $Li^+$, $Rb^+$, and $Cs^+$ have ionic radii more than $Na^+$, we need to consider their ionic radii. The ionic radii (in pm) for these ions are approximately as follows: 

Cation	Ionic Radius (pm)
$Li^+$	76
$Na^+$	102
$K^+$	138
$Rb^+$	152
$Cs^+$	167

Comparing each cation to $Na^+$ (102 pm):

• $Li^+$ (76 pm) < $Na^+$
• $K^+$ (138 pm) > $Na^+$
• $Rb^+$ (152 pm) > $Na^+$
• $Cs^+$ (167 pm) > $Na^+$

Thus, the number of cations with ionic radii more than $Na^+$ is 3. This value fits within the expected range of 3,3, confirming its correctness.

Therefore, the answer is: 3