Which gives +7 oxidation state ?

Options

A. Mn(25)
B. Cr(24)
C. Cu(29)
D. Fe(26)

Answer

A

Explanation

For d-block elements ,
oxidation state = ns electrons + (n-1) d electrons (unpaired )
(a) Mn(25) = [Ar] `3d^(5) 4s^(2)`
O.S. = 5 + 2 = 7
(b) Cr (24) = [Ar] `3d^(5) 4s^(1)`
O.S. = 5 + 1 = 6
Cu (29) = [Ar] = `3d^(10) 4s^(1)`
O.S. = 0 + 1 = 1
(d) Fe(26) = [Ar] `3d^(6) 4s^(2)`
O.S. = +2 and + 3
Thus only Mn exhibits + 7 oxidation state among the given elements .