Answer
The \[4s\] electrons are easily lost during the formation of the \[~+2\] state.
Work Step by Step
The \[+2\] state is very common for transition metals because the \[4s\] electrons are easily lost during the formation of the \[~+2\] state, as removal of electrons from the d orbitals is difficult as compared to the s orbitals.
Example:
\[Mn:\quad \left[ Ar \right]3{{d}^{5}}4{{s}^{2}}\]
In the above example, the d orbital is half-filled, due to which it requires more energy as compared to the s orbital to release electrons. So, the s orbital easily releases electrons to form the +2 state.
