Question

choose three characteristics of compounds. a compound must include silicon or carbon. the number of elements in each molecule of a compound can be different. different elements are chemically combined. the atoms in a compound are held tightly together. elements can combine only in certain ways to form compounds. compounds are rarely found on the earth.

Explanation:

A compound is a substance formed from two or more different elements chemically combined. The atoms in a compound are held together by chemical bonds. Elements combine in specific ratios and ways to form compounds. Compounds are very common on Earth. A compound doesn't have to include silicon or carbon. In a given compound, the number of elements in each molecule is fixed by its chemical formula.

Answer:

C. Different elements are chemically combined.
D. The atoms in a compound are held tightly together.
E. Elements can combine only in certain ways to form compounds.