Which of the following statements about intermolecular distances and cohesive forces between gas is correct? They are

Analyze the question: It asks about two properties of gas particles: the intermolecular distances and the cohesive forces (forces of attraction between molecules). The options pair these in order, so we need "distances = ?" and "forces = ?".

Concept (Kinetic Theory of Gases):

• Gas molecules are very far apart compared to their own size, so intermolecular distances are large.
• Because they are so far apart, the forces of attraction (cohesive forces) between them are negligible (very weak, almost zero). This is why gases have no fixed shape or volume and can spread to fill any container.

Step-by-step check of the options:

• A. Both large: Distances are large, but the forces are not large. Wrong.
• B. Both negligible: The distances are not negligible. Wrong.
• C. Constant and negligible: The distances are not constant, since molecules move randomly and collide. Wrong.
• D. Large and negligible: Large distances and negligible cohesive forces. This matches the kinetic theory. Correct.

Tip: Remember the pattern for the states of matter:

• Solids: close together, strong forces
• Liquids: close, moderate forces
• Gases: far apart, negligible forces

Whenever you see "gas" in a question about intermolecular forces, think "far apart, almost no attraction."