Why Cu, Ni and Zn generally do not show oxidation state greater than 2?

Explanation

To understand why copper (Cu), nickel (Ni), and zinc (Zn) generally do not show oxidation states greater than +2, we can analyze their electronic configurations, ionization energies, and the effective nuclear charge.

### Step-by-Step Solution:

1. **Electronic Configuration**:
- Copper (Cu): [Ar] 3d¹⁰ 4s¹
- Nickel (Ni): [Ar] 3d⁸ 4s²
- Zinc (Zn): [Ar] 3d¹⁰ 4s²
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