Particles of matter are in continuous motion.
Explanation
The phenomenon described is known as diffusion, which is the spontaneous intermixing of particles of two different types of matter. This process is fundamentally explained by the kinetic theory of matter.Detailed Analysis:
- When potassium permanganate crystals are placed in water, they break down into smaller particles.
- These particles move spontaneously from the area of high concentration (the crystal) to areas of low concentration (the surrounding water) until the mixture becomes uniform.
- This movement occurs without external force or stirring, driven solely by the intrinsic kinetic energy of the particles.
- Consequently, the spreading of colour is direct evidence that the particles of matter are not stationary but are in continuous random motion.
Analysis of Other Options:
- Particles of matter attract each other.: While particles of matter do attract each other, this force keeps the solid crystal together. The spreading occurs because the particles' kinetic energy overcomes these attractive forces.
- Particles of matter are very small.: The ability of a small crystal to colour a large volume of water demonstrates that particles are very small (divisibility), but the act of spreading is specifically due to motion.
- Matter is continuous in nature.: Matter is particulate (composed of discrete particles), not continuous. The experiment disproves the continuous nature of matter.
Key Takeaway: Diffusion is the macroscopic manifestation of the microscopic fact that particles of matter possess kinetic energy and are in a state of continuous motion.