Which of the following is a covalent compound ?

Options

A. `Al_(2)O_(3)`
B. `AlF_(3)`
C. `AlCl_(3)`
D. `Al_(2)(SO_(4))_(3)`

Answer

To determine which of the given options is a covalent compound, we can follow these steps:

### Step 1: Identify the Compounds
First, we need to identify the compounds listed in the question. For this example, let's assume the options are:
1. Al2(SO4)3
2. NaCl
3. AlCl3
4. MgO

### Step 2: Analyze Each Compound
Next, we will analyze each compound to determine whether it is ionic or covalent.

- **Al2(SO4)3**: This compound dissociates into ions (Al^3+ and SO4^2-), indicating it is ionic.
- **NaCl**: Sodium chloride is composed of Na^+ and Cl^-, which also indicates it is ionic.
- **AlCl3**: Aluminum chloride can exhibit covalent character due to the presence of a small cation (Al^3+) and a relatively larger anion (Cl^-). According to Fejan's rule, this combination favors covalent bonding.
- **MgO**: Magnesium oxide consists of Mg^2+ and O^2- ions, which indicates it is ionic.

### Step 3: Apply Fejan's Rule
According to Fejan's rule, covalent character is favored when a small cation is paired with a large anion. In our analysis:
- Al^3+ is a small cation.
- Cl^- is a larger anion compared to O^2- and SO4^2-.

Thus, AlCl3 is likely to have significant covalent character.

### Step 4: Conclusion
Based on the analysis, the compound that exhibits covalent character is AlCl3.

### Final Answer
The covalent compound among the options is **AlCl3**.

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