The oxidation states of Cr in [Cr(H2O)6]Cl3, [Cr(C6H6)2], and K2[Cr(CN)2(O)2(O2)(NH3)] respectively are :

Ans. (2)

(i) [Cr(H₂O)₆]Cl₃ : Hexaaquachromium(III) chloride
x + 6 × 0 + (–1) × 3 = 0
x = +3

(ii) [Cr(C₆H₆)₂] : bis(η⁶–benzene)chromium(0)
y + 2 × 0 = 0
y = 0
(iii) K₂[Cr(CN)₂ (O)₂ (O₂) (NH₃)] :
Potassium amminedicyanidodioxidoperoxidochromate(VI)
2 × 1 + z + 2 × (–1) + 2 × (–2) + (–2) + 0 = 0
z = +6
The oxidation states of Cr in [Cr(H₂O)₆]Cl₃, [Cr(C₆H₆)₂], and K₂[Cr(CN)₂ (O)₂ (O₂) (NH₃)] respectively are +3, 0 and +6.

[Cr(H2O)6]Cl3
x + 6(0) + 3(–1) = 0
x = +3
[Cr(C6H6)2]
x = 2(0) = 0
x = 0
K2[Cr(CN)2(O)2(O2)(NH3)]
2 + x + 2(–1) + 2(–2) + (–2) + (0) = 0
x = +6