Question

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

Explanation:

To determine why absolute zero is the lowest possible temperature, we analyze each option:

• The first option describes a phase change (ice to water) which is not related to absolute zero's definition.
• The second option states that at absolute zero, molecular motion almost stops. Absolute zero (0 K or -273.15 °C) is defined as the temperature at which the theoretical minimum molecular motion (kinetic energy) occurs, approaching zero. This directly explains why it's the lowest possible temperature as molecular motion can't decrease further.
• The third option mentions kinetic energy's relation to molecular motion but doesn't explain why absolute zero is the lowest.
• The fourth option (incomplete, likely about heat - temperature relation) is too vague and doesn't address the uniqueness of absolute zero.

Answer:

B. At absolute zero, the motion of the molecules of a substance almost stops.