Question

What evidence in Lavoisier's twelve-day experiment showed that oxygen was chemically reacting (combusting) with substances? A) He obtained less of the gas as disappeared in the last experiment. B) Lavoisier noticed that about four-fifths of the air had been used up. C) He noticed that there was a gas that did not support life or burning. D) A red oxide of mercury was formed on the surface of the mercury in the retort.

Answer 1

The answer is D for surely positive guys

Answer 2

B) He noticed four-fifths of the air had been used up. If by air this question is referring to oxygen, the fact that it has been used up means it has reacted, mean a substance has combusted.