Assertion : Non-polar molecular solids have higher melting points than polar molecular solids.
Reason : Non-polar molecular solids have weak London or dispersion forces between their molecules while polar molecules have strong dipole-dipole forces between their molecules.

Explanation

To solve the assertion and reason question, we will analyze both the assertion and the reason provided.

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- The assertion states that "Non-polar molecular solids have higher melting points than polar molecular solids."
- We need to evaluate if this statement is true or false.

2. **Understanding the Reason**:
- The reason states that "Non-polar molecular solids have weak London or dispersion forces between their molecules while polar molecules have strong dipole-dipole forces between their molecules."
- We need to determine if this statement is true or false.

3. **Analyzing the Forces**:
- Non-polar molecular solids are held together by weak London dispersion forces, which arise due to temporary dipoles in the molecules.
- Polar molecular solids, on the other hand, are held together by stronger dipole-dipole interactions. These interactions occur due to the permanent dipoles present in polar molecules.

4. **Comparing Melting Points**:
- Since non-polar molecular solids have weak intermolecular forces, they require less energy to overcome these forces, resulting in lower melting points.
- Conversely, polar molecular solids, with their strong dipole-dipole interactions, require more energy to break these forces, leading to higher melting points.

5. **Conclusion**:
- The assertion is **false** because non-polar molecular solids do not have higher melting points than polar molecular solids; they have lower melting points.
- The reason is **true** because it correctly describes the nature of the intermolecular forces in non-polar and polar molecular solids.

### Final Answer:
- **Assertion**: False
- **Reason**: True