Question

In the ground state, an element has $13$ electrons in its M-shell. The element is

• A. Manganese
• B. Chromium
• C. Nickel
• D. Iron

Answer 1

Answer: (B)

Chromium

$13e^{-}$ in M $\left(3rd\right)$ shell means $3s^{2}3p^{6}3d^5$. hence complete configuration will be $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{1}3d^5$
i.e., total $e^{-}=24$. Hence the element is chromium.