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

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