Discussion Forum



1)

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


A) +3, +4 and +6

B) +3, +2 and +4

C) +3, 0 and +6

D) +3, 0 and +4

Answer:

Option C

Explanation:

Let the oxidation state of Cr in all cases is 'x'

(i)  Oxidation state of Cr in  [Cr(H2O)6 ]Cl3

x + (0 × 6) + (-1 × 3)=0

or       x+0-3=0

or        x= +3

 (ii)  Oxidation state of Cr in [Cr(C6H6)2]

   x+(2× 0)=0

or x=0

(iii) Oxidation state of Cr in

     K2[Cr (CN)2(O)2 (O2 )(NH3)] 

    1×2+x+ (-1× 2) + (-2× 2) + (-2)+0=0

  or    2 +x-2-4-2=0

 or     x-6=0

 hence x=+6

 Thus, +3,0 and +6 is the answer