Q27 / 90 · JEE Main 2018 (08 Apr) · Chemistry

The oxidation states of $Cr$ in $[Cr {(H_{2} O)}_{6}] {Cl}_{3}, [Cr {(C_{6} H_{6})}_{2}]$ and $K_{2} [Cr {(CN)}_{2} {(O)}_{2} (O_{2}) ({NH}_{3})]$ , respectively, are:

Solution

(i)

[Cr {(H_{2} O)}_{6}] {Cl}_{3} :

Hexaaquachromium

(III)

chloride

x + 6 \times 0 + (- 1) \times 3 = 0

x = + 3

(ii)

[Cr {(C_{6} H_{6})}_{2}] : bis (η^{6} - benzene)

chromium

(0)

y + 2 \times 0 = 0

y = 0

(iii)

K_{2} [Cr {(CN)}_{2} {(O)}_{2} (O_{2}) ({NH}_{3})] :

Potassium amminedicyanido dioxide peroxide chromate

(VI)

2 \times 1 + z + 2 \times (- 1) + 2 \times (- 2) + (- 2) + 0 = 0

z = + 6

The oxidation states of

Cr

[Cr {(H_{2} O)}_{6}] {Cl}_{3}, [Cr {(C_{6} H_{6})}_{2}]

and

K_{2} [Cr {(CN)}_{2} {(O)}_{2} (O_{2}) ({NH}_{3})]

, respectively, are

+ 3, 0

and

+ 6

Hence, the correct answer is option: 'D'.