Question

Identify oxidation state of cobalt ion in the complex, \([\text{Co(NH}_3)_5\text{Br}]\text{SO}_4\) .

• A. \(+2\)
• B. \(+3\)
• C. \(+1\)
• D. \(+4\)

Hint:

Sulfate carries -2, so the complex ion is +2; ammonia is neutral and bromide is -1.

Answer 1

The Correct Option is B

Step 1: Net charge:
The compound is neutral, with one sulfate (-2), so the cation must be $+2$.

Step 2: Ligand charges:
Total ligand charge = $5\times0 + (-1) = -1$.

Step 3: Metal:
Metal charge = $+2 - (-1) = +3$, option (B).

Final Answer:
Cobalt shows oxidation state +3. \[ \boxed{\text{(B) }+3} \]