Be²⁺ is isoelectronic with which of the following ions?

Options

(a) H⁺
(b) Li⁺
(c) Na⁺
(d) Mg²⁺

Correct Answer:

Li⁺

Explanation:

Be²⁺= (4-2) = 2
is isoelectronic with Li⁺ (3-1 =2)
Since both have same number of electrons in their outermost shell.