Longitudinal waves are possible in

Options

A. solids
B. liquids
C. gases
D. All of these

Answer

To determine where longitudinal waves are possible, we will analyze the properties of longitudinal waves and the states of matter.

### Step-by-Step Solution:

1. **Understanding Longitudinal Waves**:
Longitudinal waves are waves in which the particle displacement is parallel to the direction of wave propagation. This means that the particles of the medium move back and forth in the same direction as the wave travels.

2. **Identifying the Mediums**:
Longitudinal waves can travel through different states of matter: solids, liquids, and gases.

3. **Behavior in Solids**:
In solids, longitudinal waves can propagate because the particles are closely packed together. When a force is applied, the particles compress and then return to their original position, transferring energy through the medium.

4. **Behavior in Liquids**:
In liquids, longitudinal waves can also propagate. The molecules in a liquid are not as tightly packed as in solids, but they are still close enough to transmit compressional waves. An example of this is sound traveling through water.

5. **Behavior in Gases**:
In gases, longitudinal waves can travel as well. The molecules in a gas are far apart compared to solids and liquids, but they can still compress and expand, allowing sound waves to travel through the air.

6. **Conclusion**:
Since longitudinal waves can travel through solids, liquids, and gases, the correct answer to the question is that longitudinal waves are possible in **all of these**.

### Final Answer:
**D) All of these**

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