Which of the following are not ionic?
(i) `AICl_3` (ii) `CaCl_2`
(iii) `MgCl_2` (iv) `LiCl`

Options

A. (i) and (iv)
B. (i) and (iii)
C. (ii) and (iii)
D. (iii) and (iv)

Explanation

To determine which of the compounds listed are not ionic, we need to analyze the nature of the bonds in each compound based on their constituent elements.

### Step-by-Step Solution:

1. **Identify the Compounds**: The compounds given are:
- (i) AlCl₃
- (ii) CaCl₂
- (iii) MgCl₂
- (iv) LiCl

2. **Understand Ionic vs. Covalent Bonds**:
- Ionic bonds typically form between metals and nonmetals with a significant difference in electronegativity.
- Covalent bonds form when two nonmetals share electrons, which usually occurs when the electronegativity difference is small.

3. **Analyze Each Compound**:
- **(i) AlCl₃ (Aluminum Chloride)**:
- Aluminum is a metal, and chlorine is a nonmetal. However, AlCl₃ has a covalent character due to the small size of Al and its high charge density, leading to significant covalent character. Thus, AlCl₃ is not purely ionic.
- **(ii) CaCl₂ (Calcium Chloride)**:
- Calcium is a metal, and chlorine is a nonmetal. The electronegativity difference is significant, and thus CaCl₂ is ionic.
- **(iii) MgCl₂ (Magnesium Chloride)**:
- Magnesium is a metal, and chlorine is a nonmetal. Similar to CaCl₂, the electronegativity difference is significant, making MgCl₂ ionic.
- **(iv) LiCl (Lithium Chloride)**:
- Lithium is a metal, and chlorine is a nonmetal. The electronegativity difference is also significant, indicating that LiCl is ionic.

4. **Conclusion**:
- The only compound that is not ionic among the given options is **AlCl₃**.

### Final Answer:
The compound that is not ionic is **(i) AlCl₃**.