Question

An element has 13 electrons in its M shell and 1 electron in N shell in ground state. Identify the element.

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

Answer 1

The correct option is A Chromium

M shell means it is third shell $\Rightarrow n=3$

Number of electrons in M shell=13

$\Rightarrow 3s^{2}3p^{6}3d^5$

and N shell means it is fourth shell $\Rightarrow n=4$

Number of electrons in N shell=1

$4s^1$

thus the electronic configuration is: $\left(1s^2\right)\left(2s^{2}2p^6\right)\left(3s^{2}3p^{6}3d^5\right)\left(4s^1\right)$

The element is Chromium ($Cr$).