Question

5/10
which best describes why absolute zero is the lowest possible temperature?
at absolute zero, the motion of the molecules of a substance almost stops.
because when you add heat, ice melts into water.
because of the kinetic energy of molecular motion.
because heat is related to temperature.

Explanation:

To determine the best answer, we analyze each option:

• Option 1: At absolute zero, molecular motion (kinetic energy) theoretically stops (not just "almost"), so this is partially correct but not the best explanation of "why" it's the lowest temp.
• Option 2: Melting ice is a phase change at 0°C (not related to absolute zero, which is ~ -273.15°C), so this is irrelevant.
• Option 3: Absolute zero is the temperature at which molecular kinetic energy is minimum (theoretically zero, meaning molecular motion stops). Temperature is related to average kinetic energy of molecules. So the kinetic energy of molecular motion being zero (or minimum) at absolute zero explains why it's the lowest possible temperature. This directly connects the concept of temperature to molecular kinetic energy.
• Option 4: Stating heat is related to temperature is a vague statement and does not explain why absolute zero is the lowest temperature. It does not connect to the molecular motion/kinetic energy concept which is key to understanding absolute zero.

Answer:

C. Because of the kinetic energy of molecular motion.