Question

In the complex ion [Cr(C204)2(H20)2]-, what is the oxidation number of Cr?

O A. 3+
O B. 1+
O C.2+
OD. 2-
O E. 1-

Answer 1

A. 3+

Step-by-step explanation:

In the complex, the global charge is -1.

There are 2 molecules of H₂O but water is a neutral ligand that doesn't contribute any charge to the complex

In contrast, the C₂O₄ ligand has a charge of -2. As there are 2 C₂O₄, the charge is -4.

The -4 + The charge of Cr is equal to global charge of the complex ion = -1.

Thus, Cr has a charge of +3 and right answer is:

A. 3+