A measurement of how vigorously the atoms in a substance move, i.e., the hotness or coldness.

• A. Humidity
• B. Barometric pressure
• C. Temperature
• D. Wind

Answer: (C)

Temperature is a measure of how vigorously the atoms in a substance move, reflecting the average kinetic energy of the molecules. When the particles are moving more rapidly on average, the substance feels hotter; when they move more slowly, it feels cooler. This is why temperature is the best descriptor of hotness or coldness.

Humidity describes how much water vapor is in the air, which affects comfort and humidity-related processes but not the actual motion of molecules in the same way temperature does. Barometric pressure is the force exerted by the weight of the air above you, which relates to weather and altitude but not the average speed of molecules in a substance. Wind is the bulk movement of air caused by pressure differences, not a direct measure of how fast individual molecules are vibrating or moving.