Which of the following is not a ionic solid ?

Options

A. NaCI
B. MgO
C. CsCI
D. SiC

Answer

To determine which of the following is not an ionic solid, we will analyze each option based on their constituent particles and the type of bonding present.

### Step-by-Step Solution:

1. **Identify Ionic Solids**: Ionic solids are made up of positive and negative ions held together by strong electrostatic forces of attraction. Common examples include sodium chloride (NaCl), magnesium oxide (MgO), and cesium chloride (CsCl).

2. **Analyze Each Option**:
- **NaCl (Sodium Chloride)**: This compound consists of Na⁺ and Cl⁻ ions. It is a classic example of an ionic solid.
- **MgO (Magnesium Oxide)**: This compound consists of Mg²⁺ and O²⁻ ions. It is also an ionic solid.
- **CsCl (Cesium Chloride)**: This compound consists of Cs⁺ and Cl⁻ ions. It is another example of an ionic solid.
- **SiC (Silicon Carbide)**: This compound consists of silicon and carbon atoms. The bonding in SiC is covalent, as the atoms are linked by covalent bonds rather than ionic bonds.

3. **Conclusion**: Among the given options, SiC (Silicon Carbide) is not an ionic solid; it is a covalent solid.

### Final Answer:
**SiC (Silicon Carbide) is not an ionic solid.**