Explain by giving resons of stability of completely filled and half filled subshell

Explanation

Symmetrical distribution of electron : The completely fille or half filled subshell have and are therefore relatively small the electrons are more strongly attracted by the nucleus.

Exchange energy : The stabilizing effect arises whenever two or more electrons with the same and the energy released due to this exchange in called exchange energy .
if `d^(5)` electron configuration all five electron have take place and more energy release and os `d^(5)` is more stable configuration .
So half filled and completely filled `3d^(5) ` and `3d^(10)` posses more stability
(i) Relatively small shielding
(ii) Smaller coulombic repulsion energy and
(iii) larger exchange energy.