All elements are pure substances.

true

false

It can be a compound or a single element. An element is a pure substance that cannot be separated into simpler substances by chemical or physical means. There are about 117 elements, but carbon, hydrogen, nitrogen and oxygen are only a few that make up the largest portion of Earth.
hopefully that helps

The correct answer is "false"

The mole ratio of hydrogen to ammonia is 3: 2.