Question

Oxidation numbers of P in PO₄^3- , of S in SO₄^2- and that of Cr in Cr₂O₇^2- are respectively

(a) +3, +6 and +5 

(b) +5, +3 and +6

(c) -3, +6 and +6 

(d) +5, +6 and +6

Answer 1

The correct option is: (d) +5, +6 and +6

Explanation:

Let oxidation number of P in PO₄^3- be x.

. ^.. x + 4(-2) = -3 => x = +5

Let oxidation number of S in SO₄^2- be y.

. ^.. y + 4(-2) = -2 => y = +6

Let oxidation number of Cr in Cr₂O₇^2- be z.

. ^.. 2z + 7(-2) = -2 => z = +6