The sharp melting point of crystalline solids is due to ……..

Options

A. a regular arrangement of consitituent particles observed over a short distance in the crystal lattice .
B. a regular arrnagment of constituent particles observed over a long distance in the crystal lattice.
C. same arrangement of consitituent particles in different direction.
D. different arrangement of constituent particles in different directions.

Answer

To answer the question regarding the sharp melting point of crystalline solids, we can break down the explanation into clear steps:

### Step-by-Step Solution:

1. **Understanding Melting Point**:
- The melting point of a substance is the temperature at which it changes from solid to liquid. For crystalline solids, this transition occurs at a specific temperature, known as the sharp melting point.

2. **Definition of Sharp Melting Point**:
- A sharp melting point indicates that the solid will melt at a precise temperature (let's say x degrees Celsius). Below this temperature, the solid remains intact, and above this temperature, it is already in the liquid state.

3. **Crystalline Structure**:
- Crystalline solids have a well-defined and ordered arrangement of particles (atoms, ions, or molecules) in a three-dimensional lattice structure. This regular arrangement is crucial for their properties.

4. **Long-Range Order**:
- The key feature of crystalline solids is their long-range order. This means that the arrangement of particles is consistent and repeats over large distances. For instance, if you take a piece of a crystalline solid from one end to another, the arrangement of particles will remain uniform throughout.

5. **Short-Range Order**:
- While crystalline solids exhibit long-range order, they also have short-range order, meaning that at a very small scale, the arrangement of particles is also regular. This short-range order contributes to the sharp melting point.

6. **Conclusion**:
- The sharp melting point of crystalline solids is primarily due to the regular arrangement of constituent particles observed over a long distance in the crystal lattice. This uniformity ensures that the melting point remains consistent regardless of where the sample is taken from within the crystal.

### Final Answer:
The sharp melting point of crystalline solids is due to a regular arrangement of constituent particles observed over a long distance in the crystal.

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