Question

An ideal gas is heated in a closed container at constant volume. Which of the following properties of the gas increases as the gas is heated?

• A. The atomic mass of the atoms in the molecules
• B. The number of molecules
• C. The density of the gas
• D. The pressure exerted by the molecules on the walls of the container
• E. The average space between the molecules

Answer 1

The correct option is D The pressure exerted by the molecules on the walls of the container

The ideal gas law states that temperature is directly proportional to pressure and volume. Since the gas is in a closed container, the volume is fixed, so an increase in temperature leads to an increase in pressure. The correct answer is D.

The atomic mass and the number of molecules are fixed properties of the gas sample, and cannot change with heat. The density depends on the mass and the volume. The mass is also a fixed property of the gas sample, and the volume is being held constant, since we are dealing with a closed container. Therefore, the density must also remain constant. Because the number of molecules and the volume are constant, the average space between the molecules must remain constant.