Question

The smallest ion among the following is:

• A. $N{a}^{+}$
• B. $M{g}^{2+}$
• C. $A{l}^{3+}$
• D. $S{i}^{+4}$

Answer 1

The correct option is D

$S{i}^{+4}$

1. All the given four options are isoelectronic species (Species, where the number of electrons is same but nuclear charge, is different))
2. A charged atom or molecule is known as an ion. Cations are positively charged ions, while anions are negatively charged ions.
3. The more the nuclear charge on an ion, the more strongly electrons are attracted, and hence the size of the ion contracts. Hence here $\left(S{i}^{+4}\right)$ is the smallest of all the given options.
4. The Sequence would be $\mathit{S}{\mathit{i}}^{\mathbf{+}\mathbf{4}}\mathbf{}\mathbf{<}\mathbf{}\mathit{A}{\mathit{l}}^{\mathbf{+}\mathbf{3}}\mathbf{}\mathbf{<}\mathit{M}{\mathit{g}}^{\mathbf{+}\mathbf{2}}\mathbf{}\mathbf{<}\mathit{N}{\mathit{a}}^{\mathbf{+}}$

Option (D) is correct and option (A), (B) and (C) are incorrect.