Question

The atomic number of an element ${}^{\prime }{M}^{\prime }$ is $26$. How many electrons are present in the M-shell of the element in its $M^{3+}$ state?

• A. $11$
• B. $15$
• C. $14$
• D. $13$

Answer 1

Answer: (D)

$13$

An atomic number of element M is 26.

Electronic configuration is $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^6$

first 2 electrons are removed form 4s shell then from 3d shell.

$M^{+3}$ electronic configuration will be $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}3d^5$

K-shell is n=1

L shell is n=2

M shell is =3.

For M shell, no. of electrons present will be $2+6+5=13$ electrons.

Hence, the correct option is $D$.