Question

What is the atomic number of the element with $M^{2+}$ ion having electronic configuration $\left[Ar\right]3d^8$?

• A. $25$
• B. $28$
• C. $27$
• D. $26$

Answer 1

Answer: (B)

$28$

$E.C$ of $M:\left[Ar\right]4s^{2}3d^8$

$E.C$ of $M^{2+}:\left[Ar\right]4s^{0}3d^8$

Total electrons $=28=$ atomic number.