Question

Fill in the blanks :
__________ is a pure substance which is made up of only one kind of atoms.

Answer 1

Atom:

1. The smallest unit of ordinary matter that makes up a chemical element is an atom.
2. Atoms that are neutral or ionized make up every solid, liquid, gas, and plasma.

Element:

1. A pure substance that is made up of only one kind of atom is called an element.
2. For example, Hydrogen (${\text{H}}_2$), Oxygen (${\mathrm{O}}_2$), etc.

Hence, Element is a pure substance which is made up of only one kind of atoms.