Which of the following elements does not show variable covalency?
AI, P, S, CI

Explanation

To determine which of the given elements does not show variable covalency among Aluminium (Al), Phosphorus (P), Sulfur (S), and Chlorine (Cl), we can analyze the electronic configurations and the ability of these elements to form different covalent bonds.

### Step 1: Understand Covalency
Covalency refers to the number of electrons an atom can share with other atoms to form covalent bonds. Some elements can show variable covalency, meaning they can form different numbers of bonds depending on their oxidation states.

### Step 2: Analyze Each Element
1. **Aluminium (Al)**:
- Group: 13
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