Which of the following is true about compounds?
1) they can be physically separated into their component elements.
2) they have properties similar to those of their component elements.
3)they have compositions that vary.
4) they are substances.

4) They are substances.

Explanation:

Compounds are substances that are made up of two or more kind of atoms that are chemically bonded together.

The properties of a compound is distinct and different from those of the individual elements that combines to make it up.

What then is a substance?

Any matter be it solid, liquid or gas with a specific composition is a substance. For example, NaCl is common salt and its chemical properties are uniform in all parts but sea water is not a substance as it is made up of water, mineral salts, dissolved gases etc.

1. They can be physically separated into their component elements. (Fasle)

Compound are two or more elements chemically combined together. They cannot be physically separated by simple separation methods.

2. They have properties similar to those of their component elements. (false)

Compounds have different physical and chemical properties to those of their component elements.

3. They have composition that vary (false)

Compounds have fixed composition.

4. They are substances (true)

Compounds is the combination of two or more elements be it solid, liquid or gas to form a chemical substance.

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