How did lavoisier distinguish between compounds and elements?

Anybody wanna ? (picture included? )

Give one example to show that when substances are mixed, it may result in a chemical or a physical change depending on the conditions.

During cooling, the kinetic energy of the molecules falls. why does this happen? a. the motion of the molecules increases. b. the motion of the molecules slows down. c. the van der waals forces between molecules decrease d. the forces of attraction between the molecules are overcome.