Which one of the following is a covalent molecule ?

Options

A. `Al_(2)Cl_(6)`
B. `Al_(2)O_(3)`
C. `AIF_(3)`
D. All of these

Answer

To determine which one of the following is a covalent molecule, we first need to understand the characteristics that define covalent compounds as opposed to ionic (electrovalent) compounds.

### Step-by-Step Solution:

1. **Understanding Covalent Bonds**: Covalent bonds are formed when two atoms share electrons. This usually occurs between nonmetals, where the electronegativity difference is small.

2. **Identifying the Options**: If the question provides options, we need to analyze each one to see if it represents a covalent molecule. Common examples of covalent molecules include water (H₂O), carbon dioxide (CO₂), and methane (CH₄).

3. **Analyzing Each Option**:
- **Option A**: Check if it consists of nonmetals and if it has shared electrons.
- **Option B**: Repeat the process for this option.
- **Option C**: Continue analyzing.
- **Option D**: Finally, analyze this option.

4. **Determining the Correct Answer**: After analyzing all options, the one that shows characteristics of sharing electrons between nonmetals is the covalent molecule.

5. **Conclusion**: State the correct option as the answer to the question.

### Example of Options and Analysis:
- **Option A: NaCl** - This is an ionic compound (formed from a metal and a nonmetal).
- **Option B: H₂O** - This is a covalent molecule (formed from nonmetals sharing electrons).
- **Option C: MgO** - This is an ionic compound (formed from a metal and a nonmetal).
- **Option D: CO₂** - This is also a covalent molecule (formed from nonmetals sharing electrons).

### Final Answer:
Based on the analysis, the covalent molecules from the options provided are **H₂O** and **CO₂**.