What may be the stable oxidation state of the transition element with the following d electron configurations in the ground state of their atoms : `3d^(3),3d^(5),3d^(8)`and `3d^(4)`?

Explanation

`3d^(3)4s^2=+5`,`3d^(5)4s^1=+6`
`3d^(5)4s^2=+2,+7,3d^(8)4s^2=+2`
`3d^(5)4s^(2)=3d^(5)4s^(1)=+6` and `+3`
The maximum oxidation states of reasonable stability correspond to the sum of s and d-electrons up to Mn. After that, there is abrupt decrease in the stability of higher oxidation states.