The chemical formula for an emerald is Be3Al2(SiO3)6. An emerald can be described as a pure substance because it is a compound.
a pure substance because it is an element.
an impure substance because it is chemically combined.
an impure substance because it is a mixture.

plants need sunlight, water, and carbon dioxide to make food. plants use the raw materials of water, nutrients they absorb from soil, and carbon dioxide to make sugars the plant can use. energy from the sun and chlorophyll are also needed.

answer; the numbers of valence electrons in the acetic acid molecule (ch3co2h) is 24;