instruction:
Given a scientific question and its correct answer, generate supporting facts for the answer. This supporting fact can be an explanation for the answer to the given question.
question:
Question: What are molecules that the immune system recognize as foreign to the body? Answer: antigens
answer:
The average kinetic energy of atoms (each of mass and average speed ) in a gas is related to the temperature of the gas, measured in Kelvin. The Boltzmann constant is a constant of nature, equal to.

question:
Question: When volume does not change, temperature is proportional to what other property? Answer: pressure
answer:
Pressure and temperature at constant volume are directly proportional.

question:
Question: The substances that comprise heterogeneous mixtures can also be separated by what means? Answer: physical
answer:
The substances that comprise heterogeneous mixtures can also be separated by physical means. We will discuss separation techniques in the following lesson.