Question

A gas in a closed container is steadily heated over a period of time. Which of the following statements is true of this process?

• A. The average kinetic energy of the gas molecules decreases
• B. The mass of the container increases
• C. The pressure exerted by the gas on the walls of the container increases
• D. The gas changes phase into a liquid
• E. The specific heat of the gas decreases

Answer 1

The correct option is C The pressure exerted by the gas on the walls of the container increases

The answer to this question is C . The key lies in remembering the ideal gas law: PV = nRT . According to this formula, an increase in temperature is accompanied by an increase in pressure. A is wrong, since the average kinetic energy of gas molecules corresponds to their temperature: if the temperature increases, so does the average kinetic energy of the molecules. B is wrong because were dealing with a closed container: the mass cannot either increase or decrease. D is wrong because a gas must be cooled, not heated, to change phase into a liquid. Finally, E is wrong because the specific heat of any substance is a constant, and not subject to change.