Which of the following statements is NOT correct?

Analysis of the Question

The question asks you to identify the incorrect statement among the four options provided regarding the nature of matter and the kinetic theory of matter.

Concept Explanation: The Kinetic Theory of Matter

To solve this, we must look at the fundamental principles of the Kinetic Theory of Matter:

1. Matter is particulate: All matter is made up of tiny, discrete particles called atoms or molecules.
2. Constant motion: These particles are in a state of continuous, random motion (this is what causes phenomena like diffusion and Brownian motion).
3. Intermolecular forces: There are forces of attraction between these particles.
4. Temperature relationship: The kinetic energy of these particles increases as the temperature increases.

Step-by-Step Evaluation

• Option A: Brownian motion is the random, zig-zag movement of particles suspended in a fluid. It is a direct result of the continuous bombardment of these particles by the fast-moving molecules of the fluid. This is indeed evidence that matter is made of particles. (Correct statement)
• Option B: Atoms are the building blocks of matter. When atoms bond together, they form molecules (e.g., two Hydrogen atoms and one Oxygen atom form a water molecule). (Correct statement)
• Option C: The kinetic theory explicitly states that molecules of matter are always in constant motion, even in solids (where they vibrate about fixed positions). Therefore, stating they are not in constant motion contradicts the fundamental laws of physics. (Incorrect statement)
• Option D: This is the basic definition of matter in physics and chemistry. (Correct statement)

Conclusion

Since the question asks for the statement that is NOT correct, Option C is the right choice because it contradicts the established kinetic theory of matter.

Exam Tip

When you see questions about the "Kinetic Theory of Matter," always remember the acronym "C.A.M.":

• Constant motion.
• Atoms/Molecules (matter is made of these).
• Motion increases with temperature. If an option says particles are "stationary" or "not in motion," it is almost certainly the wrong statement!