The characteristic features of solids are:

Options

A. Definite shape
B. Definite size
C. Definite shape and size
D. Definite shape, size and rigidity

Answer

To answer the question regarding the characteristic features of solids, we can break down the solution into several key points:

### Step-by-Step Solution:

1. **Defined Shape**: Solids maintain a fixed shape that does not change unless a force is applied. This is one of the primary characteristics that distinguishes solids from liquids and gases.

2. **Defined Volume**: Solids have a definite volume, meaning they occupy a specific amount of space. Unlike gases, which can expand to fill their container, solids retain their volume regardless of the surrounding environment.

3. **Rigidity**: Solids are rigid, meaning they do not easily deform under stress. This rigidity is due to the strong intermolecular forces that hold the particles in fixed positions.

4. **High Melting Point**: Most solids have high melting points compared to liquids and gases. This is because a significant amount of energy is required to overcome the strong intermolecular forces holding the solid together.

5. **Incompressibility**: Solids are generally incompressible, meaning that their volume does not change significantly under pressure. This is a result of the closely packed arrangement of particles in a solid.

6. **Defined Size**: Solids have a defined size, which is a consequence of their fixed shape and volume. This characteristic is crucial in distinguishing solids from other states of matter.

### Conclusion:
Based on the above characteristics, the correct answer to the question is that the characteristic features of solids include defined shape, defined size, and rigidity.

### Final Answer:
The characteristic features of solids are defined shape, size, and rigidity.

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