Question

what is absolute zero?
a. the temperature at which molecules stop moving
b. the temperature referenced at 0 on the celsius scale
c. the freezing point of pure water at sea level
d. the temperature at the coldest point of outer space

Explanation:

Absolute zero is a fundamental concept in physics. According to the kinetic - molecular theory, temperature is related to the motion of molecules. As the temperature decreases, the motion of molecules slows down. At absolute zero (\(T = 0\space K\) or \(T=- 273.15^{\circ}C\)), the theoretical lowest temperature, the motion of molecules (in an ideal gas situation, translational motion) stops.

• Option B: \(0^{\circ}C\) on the Celsius scale is not absolute zero. Absolute zero is \(-273.15^{\circ}C\).
• Option C: The freezing point of pure water at sea level is \(0^{\circ}C\), which is not absolute zero.
• Option D: The coldest point of outer space is not absolute zero. There is still some residual heat and molecular motion (although very low) in outer - space regions.

Answer:

A. The temperature at which molecules stop moving