Question

The set representing the correct order of ionic radii is:

• A. ${Li}^{+}>{Be}^{2+}>{Na}^{+}>{Mg}^{2+}$
• B. ${Na}^{+}>{Li}^{+}>{Mg}^{2+}>{Be}^{2+}$
• C. ${Li}^{2+}>{Na}^{+}>{Mg}^{2+}>{Be}^{2+}$
• D. ${Mg}^{2+}>{Be}^{2+}>{Li}^{+}>{Na}^{+}$

Answer 1

The correct option is B ${Na}^{+}>{Li}^{+}>{Mg}^{2+}>{Be}^{2+}$

The ionic radius in general increases on moving from top to bottom in a group and decreases on moving from left to right in a period.

Hence, correct order is

$\underset{0.95\mathring{A}}{{Na}^{+}}>\underset{0.68\mathring{A}}{{Li}^{+}}>\underset{0.65\mathring{A}}{{Mg}^{2+}}>\underset{0.63\mathring{A}}{{Be}^{2+}}$