Question

$B{e}^{2+}$ is isoelectronic with which of the following ions?

• A. $H^{+}$
• B. $L{i}^{+}$
• C. $N{a}^{+}$
• D. $M{g}^{2+}$

Answer 1

The correct option is B $L{i}^{+}$

Isoelectronic species contains same number of electrons.
$$\begin{array}{ccc}& \text{Species}& \text{Number of electrons}\\ & B{e}^{2+}& 2\\ & H^{+}& 0\\ & L{i}^{+}& 2\\ & N{a}^{+}& 10\\ & M{g}^{2+}& 10\end{array}$$