NECO 2001 Physics · Question 23

Which statement is NOT correct about molecules?

Options

A.The number of molecules in a unit volume of a solid is greater than that in a unit volume of a liquid or gas.
B.Molecules are made up of atoms
C.The force of attraction between two molecules of a solid is greater than that between two molecules of a liquid or gas
D.Molecules of gases are in regular motion
E.Molecules of a solid vibrate about their mean positions.

Answer: D. Molecules of gases are in regular motion

Explanation written with AI and checked against the answer key

Analyze the question: We need the statement that is false about molecules. So we test each option.

Concept: According to the kinetic theory of matter:

Solids: molecules are closely packed, with strong intermolecular forces, and they vibrate about fixed (mean) positions.
Liquids: molecules are close but can slide past one another, with weaker forces.
Gases: molecules are far apart, with very weak forces, and they move randomly (in all directions, at various speeds) in constant, rapid motion.

Checking each option:

A. Solids are denser, so more molecules per unit volume than in liquids or gases. Correct.
B. Molecules are made up of atoms (e.g. H₂O has 2 hydrogen atoms and 1 oxygen atom). Correct.
C. Intermolecular forces are strongest in solids. Correct.
D. Gas molecules are in regular motion. Incorrect. Their motion is random and irregular (Brownian motion is evidence of this), so there is no ordered pattern.
E. Solid molecules vibrate about their mean positions. Correct.

Answer: The statement that is NOT correct is D.

Tip: In kinetic theory questions, watch for words like "regular" or "orderly" applied to gases. Gas molecules always move randomly. Solids = vibrate, liquids = slide, gases = random and free.

AI can make mistakes. Report anything that looks wrong.