Question

Find EAN of element in following complex \(K_{3}[\text{Cr}(\text{C}_{2}\text{O}_{4})_{3}]\).

• A. \(31\)
• B. \(65\)
• C. \(33\)
• D. \(48\)

Hint:

Find the oxidation state of Cr, then use EAN = Z minus oxidation state plus 2 times the number of donor atoms.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept
Effective atomic number: \(\text{EAN}=Z-\text{(oxidation state)}+2\times\text{(coordination number)}\).

Step 2: Oxidation state of Cr
Oxalate \(\text{C}_{2}\text{O}_{4}^{2-}\) has charge \(-2\) and three potassium ions give \(+3\).
\(x+3(-2)=-3\), so \(x=+3\).

Step 3: Coordination number
Oxalate is bidentate, so three oxalates give coordination number \(=6\).

Step 4: Calculation
\(Z=24\).
\(\text{EAN}=24-3+2\times 6=33\).

Final Answer:
The EAN of chromium in the complex is 33. \[ \boxed{\text{(C) }33} \]