**Introduction**

The particles of solids, liquids, and gases have different molecules due to the arrangement and behavior of their constituent particles. These differences arise from the unique characteristics of each state of matter and the forces acting between the particles.

**Solids**

Solids are characterized by a tightly packed arrangement of particles. The molecules in solids are held together by strong intermolecular forces, such as metallic bonds, covalent bonds, or intermolecular forces like van der Waals forces. These forces are responsible for the fixed shape and volume of solids. The molecules in solids are closely packed and vibrate in fixed positions, maintaining a regular geometric arrangement.

**Liquids**

Liquids possess more freedom of movement compared to solids. The molecules in liquids are still attracted to each other, but the intermolecular forces are weaker than in solids. This allows the particles to move more freely, though they remain in close proximity. The arrangement of molecules in liquids is less orderly and more random compared to solids.

**Gases**

Gases have the highest degree of freedom among the three states of matter. The molecules in gases have weak intermolecular forces and are widely separated. They move independently, randomly, and at high speeds. Gases do not have a definite shape or volume, as they expand to fill the container they are in.

**Factors affecting molecular behavior**

Several factors determine the behavior and arrangement of molecules in each state of matter:

1. **Intermolecular forces**: The strength of intermolecular forces determines the degree of attraction between molecules. Solids have strong intermolecular forces, liquids have intermediate forces, and gases have weak forces.

2. **Energy**: The amount of energy possessed by the molecules affects their movement and arrangement. In solids, the energy is low, resulting in a fixed arrangement. Liquids have slightly higher energy, allowing molecules to move more freely. Gases have high energy, enabling molecules to move rapidly and independently.

3. **Density**: The density of a substance depends on the arrangement and spacing of its molecules. Solids have the highest density due to their closely packed arrangement. Liquids have a lower density, and gases have the lowest density due to their widely separated molecules.

4. **Temperature and pressure**: Temperature and pressure play a crucial role in determining the state of matter. Increasing temperature and decreasing pressure can convert a substance from a solid to a liquid and then into a gas, as they affect the energy and intermolecular forces.

**Conclusion**

In summary, the particles of solids, liquids, and gases have different molecules due to the varying arrangement, behavior, intermolecular forces, energy, density, temperature, and pressure associated with each state of matter. These factors contribute to the unique characteristics and properties exhibited by solids, liquids, and gases.

As they have different intermolecular forces so force acting on the molecules is different