Kinetic Molecular Theory and Gas Pressure

Steps:

• Heating the air increases the average kinetic energy of gas molecules.
• Higher kinetic energy means molecules move faster.
• In a sealed can, volume and number of molecules remain constant.
• Faster molecules collide more frequently and forcefully with the can walls, increasing pressure.

Why A is correct:

• According to the kinetic molecular theory, gas pressure results from molecular collisions with container walls; increased temperature raises collision frequency, directly boosting pressure (from ideal gas law PV = nRT, where T rise at constant V increases P).

Why the others are wrong:

• B: Heating does not change the mass of molecules; mass is invariant.
• C: In a sealed can, the number of molecules and volume are fixed, so molecules per unit volume stays the same.
• D: At constant volume, average molecular separation depends on number density, which does not increase with heating.

Final answer: A