**Correct Option: C. Gas particles are far apart and move freely, occupying the entire volume of their container.** ### Detailed Explanation: To understand why option C is the correct answer, we need to compare the behavior of gas particles with that of solid and liquid particles. 1. **Particle Arrangement**: - **Solids**: In solids, particles are closely packed together in a fixed arrangement. They vibrate in place but do not move freely. This close packing gives solids a definite shape and volume. - **Liquids**: In liquids, particles are still close together but not in a fixed position. They can slide past one another, which allows liquids to take the shape of their container while maintaining a definite volume. - **Gases**: In gases, particles are much farther apart compared to solids and liquids. They are not held together by strong intermolecular forces, allowing them to move freely and rapidly in all directions. This means that gases will expand to fill the entire volume of their container, regardless of its shape. 2. **Intermolecular Forces**: - **Solids**: Strong intermolecular forces keep the particles in fixed positions, resulting in a rigid structure. - **Liquids**: Intermolecular forces are weaker than in solids, allowing particles to move around each other while still being close together. - **Gases**: The intermolecular forces in gases are very weak, which is why gas particles can move independently of one another and are not confined to a specific volume or shape. 3. **Volume and Shape**: - **Solids**: Have a definite shape and volume. - **Liquids**: Have a definite volume but take the shape of their container. - **Gases**: Have neither a definite shape nor a definite volume. They expand to fill the entire space available to them. ### Why Other Options Are Incorrect: - **Option A**: "Gas particles are closely packed and vibrate in fixed positions." - This statement describes solids, not gases. Gas particles are not closely packed; they are far apart and move freely. - **Option B**: "Gas particles have strong intermolecular forces and maintain a definite shape." - This is also incorrect because gas particles have weak intermolecular forces, which allows them to move freely and not maintain a definite shape. - **Option D**: "Gas particles have a definite volume but no definite shape." - This statement is misleading. Gases do not have a definite volume; they expand to fill the volume of their container. This is a key characteristic that distinguishes gases from solids and liquids. ### Summary of Key Points: - Gas particles are far apart and move freely, allowing them to occupy the entire volume of their container. - Unlike solids and liquids, gases do not have a definite shape or volume due to weak intermolecular forces. - Understanding the differences in particle arrangement and intermolecular forces is crucial for distinguishing between the three states of matter. ### Revision Summary: - Gases have particles that are far apart and move freely. - They occupy the entire volume of their container and do not have a definite shape or volume. - Solids have fixed positions and definite shapes, while liquids have a definite volume but take the shape of their container. - Weak intermolecular forces in gases allow for their unique behavior compared to solids and liquids.