Question

The electronic configuration of a dipositive metal ion $M^{2+}$ is $2,8,14$ and its ionic weight is $56$. The number of neutrons in its nucleus would be:

• A. $30$
• B. $32$
• C. $34$
• D. $42$

Answer 1

The correct option is A $30$

Dipositive ion has $24$ electrons and hence atom of the metal will have $26$ electrons and $26$ protons.

No. of neutrons = Atomic wt. - No. of protons

$=56-26$

$=30$

Hence, option $A$ is correct.