Question

The value of $x$ in the complex ion [Ni(CN)$_4$]$^x$ is –

• A. 0
• B. +2
• C. –2
• D. 4

Hint:

Always calculate the overall charge on a complex ion by adding the metal oxidation state and the charges of all ligands. CN$^-$ contributes –1 each.

Answer 1

The Correct Option is C

Step 1: Assign charges.
- Let oxidation state of Ni = $y$.
- Each CN$^-$ ligand carries a charge of –1.
- Total number of ligands = 4.

Step 2: Write the charge balance equation.
\[ y + 4(-1) = x \]

Step 3: Consider Ni oxidation state.
Nickel generally shows +2 oxidation state in complexes. So, $y = +2$.

Step 4: Substitute values.
\[ (+2) + 4(-1) = x \] \[ 2 - 4 = -2 \] \[ x = -2 \] Step 5: Final Answer.
Hence, the value of $x$ in [Ni(CN)$_4$]$^x$ is –2.
\[ \boxed{-2} \]