Which of the following statements about a gas is NOT correct?

Step 1: Analyze the question We need the statement that is NOT correct about a gas, so we test each option against the kinetic theory of gases.

Step 2: The concept In a gas, the molecules are very far apart compared with their own size. There are only weak intermolecular forces, and the molecules move rapidly and randomly in all directions.

Step 3: Check each option

• A. It has no definite shape. Correct. A gas takes the shape of its container.
• B. It is compressible. Correct. There is a lot of empty space between the molecules, so a gas can be squeezed into a smaller volume.
• C. Its molecules are closely packed. Not correct. Gas molecules are widely spaced. Closely packed molecules describe solids, and to a lesser extent liquids.
• D. Its molecules gain kinetic energy when heated. Correct. Temperature is a measure of the average kinetic energy of the molecules, so heating raises it.
• E. Its molecules move about randomly. Correct. This is Brownian-type random motion, a basic assumption of kinetic theory.

Step 4: Answer The false statement is C.

Tip: For "which is NOT correct" questions, test each option one at a time. Remember the key contrast: solids have molecules closely packed, while gases have molecules far apart and highly compressible. Whenever you see "gas" paired with "closely packed", it is almost certainly the wrong statement.