Question

Coordination number and oxidation number of $Cr$ in $K_3\left[Cr\right(C_2{O}_4{)}_3]$ are respectively:

• A. 4 and +2
• B. 6 and +3
• C. 3 and +3
• D. 3 and 0

Answer 1

The correct option is B 6 and +3

Oxalate ion is bidentate, so the coordination number is 6.
$3+x-6=0$
$x=3$
The oxidation number of $Cr$ in the given compound is 3.

Option B is correct.