Why are all of the substances on the periodic table classified as elements?

Nonmetals: The term "nonmetals" is used to classify hydrogen (H), carbon (C), nitrogen (N), phosphorus (P), oxygen (O), sulfur (S) and selenium (Se). Halogens: The halogen elements are a subset of the nonmetals. They comprise Group 17 of the periodic table, from fluorine (F) through astatine (At).

The options are:

Substances on the periodic table cannot be broken down into other substances and are therefore elements.

Substances on the periodic table can be combined to form compounds and are therefore elements.

Substances on the periodic table cannot be dissolved in water or other liquids.

All elements are pure substances.

The correct answer is:

Substances on the periodic table cannot be broken down into other substances and are therefore elements.

Explanation:

An element often leads to a chemical element, a pure object of one type of atom. An element is a part or character of something abstract, particularly one that is fundamental or characteristic.