**Correct Option: C. Gas particles move freely and are far apart from each other.** ### Detailed Explanation: To understand why option C is the correct answer, we need to look at the fundamental properties of gases, solids, and liquids. 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 contrast, gas 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 fill the entire volume of their container. 2. **Movement of Particles**: - **Solids**: The particles in solids can only vibrate around fixed positions, which is why solids maintain their shape. - **Liquids**: The particles in liquids can move around each other, which allows liquids to flow and take the shape of their container. - **Gases**: Gas particles move rapidly and randomly in all directions. This high kinetic energy and the large distances between particles mean that gases can expand to fill any available space. 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 volume of their container, which is a direct result of the particles being far apart and moving freely. ### 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 do not vibrate in fixed positions. Instead, they move freely. - **Option B: Gas particles have definite shapes and volumes.** - This is incorrect because gases do not have a definite shape or volume. They take the shape of their container and can expand to fill any volume available. - **Option D: Gas particles are incompressible and do not expand.** - This statement is false. Gases are compressible, meaning they can be compressed into a smaller volume. They also expand to fill the container they are in. This is a key characteristic of gases, unlike solids and liquids, which are generally incompressible. ### Summary of Key Points: - Gas particles are far apart and move freely, allowing them to fill the volume of their container. - Unlike solids and liquids, gases do not have a definite shape or volume. - The high kinetic energy of gas particles contributes to their ability to expand and compress. - Understanding the behavior of gas particles is crucial for grasping concepts in gas laws and thermodynamics. This comprehensive understanding of gas behavior compared to solids and liquids is essential for mastering concepts in chemistry related to states of matter and their properties.