Kinetic Energy and Temperature in Heating/Cooling Processes

Steps:

• Average kinetic energy of particles is directly proportional to the absolute temperature of the substance.
• In pot X, heat is removed, causing the water to cool below boiling point, so temperature decreases.
• In pot Y, water boils steadily, maintaining constant temperature at 100°C during phase change.
• Thus, KE decreases in X but remains unchanged in Y.

Why B is correct:

• Kinetic theory states average KE = (3/2)kT, so KE changes only with temperature; cooling lowers T in X, while boiling holds T constant in Y.

Why the others are wrong:

• A: Pot Y's KE does not increase, as boiling keeps T fixed.
• C: Pot X's KE decreases with cooling, not stays the same.
• D: Pot X's KE decreases as it cools.

Final answer: B