Kinetic Molecular Theory Explains Pressure Increase

Steps:

• Heating raises air temperature, increasing average kinetic energy of molecules.
• Molecules move faster due to higher kinetic energy in fixed volume.
• Faster speed results in more frequent collisions with container walls.
• Each collision imparts greater momentum, raising total force on walls, thus pressure.

Why C is correct:

• Kinetic theory states pressure $P = \frac{1}{3} \rho v_{rms}^2$, where (root mean square speed) increases with temperature, leading to more frequent and forceful wall collisions.

Why the others are wrong:

• A: Molecules are point particles that don't expand; only their motion changes.
• B: Heating increases molecular speed, not keeps it the same.
• D: Fixed volume prevents molecules from moving further apart; density remains constant.

Final answer: C