The atomic number of an element 'M' is 26. How many electrons are present in the M-shell of the element in its M³⁺ state ?

An atomic number of element M is 26.

Electronic configuration is 1s²2s²2p⁶3s²3p⁶4s²3d⁶

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

M⁺³ electronic configuration will be 1s²2s²2p⁶3s²3p⁶3d⁵

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.