Which of the following solid has maximum melting points?

Options

A. `NaCl`
B. Ice
C. Dry ice
D. `SiO_(2)`

Answer

To determine which of the given solids has the maximum melting point, we will analyze each option based on their bonding types and structures.

### Step-by-Step Solution:

1. **Identify the Solids**: The solids given are:
- NaCl (Sodium Chloride)
- Ice (Solid Water)
- Dry Ice (Solid Carbon Dioxide, CO2)
- Si (Silicon)

2. **Analyze NaCl**:
- NaCl is an ionic solid.
- It has a face-centered cubic (FCC) structure where Na⁺ and Cl⁻ ions are arranged in a lattice.
- Ionic bonds are strong due to the electrostatic attraction between oppositely charged ions.
- The melting point of NaCl is approximately 800 °C.

3. **Analyze Ice**:
- Ice is a molecular solid formed by hydrogen bonds between water molecules.
- The melting point of ice is 0 °C.
- Hydrogen bonds are relatively weaker compared to ionic bonds.

4. **Analyze Dry Ice**:
- Dry ice is solid CO2, which is a molecular solid.
- It sublimates at -78.5 °C, meaning it transitions directly from solid to gas without melting at room temperature.
- The melting point of dry ice is around -56.6 °C, which is significantly lower than that of ice and NaCl.

5. **Analyze Silicon (Si)**:
- Silicon is a covalent network solid.
- It has a diamond-like structure where each silicon atom is covalently bonded to four other silicon atoms (sp³ hybridization).
- The melting point of silicon is approximately 1414 °C, which is very high due to the strong covalent bonds that require a lot of energy to break.

6. **Comparison of Melting Points**:
- NaCl: ~800 °C
- Ice: 0 °C
- Dry Ice: ~-56.6 °C
- Silicon: ~1414 °C

7. **Conclusion**:
- Among the given solids, Silicon (Si) has the maximum melting point of approximately 1414 °C.

### Final Answer:
Silicon (Si) has the maximum melting point among the given solids.

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