Question

Which one of the following is not an element?
A. Diamond.
B. Ozone.
C. Silica.
D. Graphite.

Answer 1

There are many differences between molecules and elements. An element is the smallest piece of chemical material, which is the basic unit of mass and considering every element. Every substance on earth has a chemical composition that is a compound that has mass and occupies space and is made up of atoms.

Complete step by step answer:
An atom is a particle of matter which characterizes a chemical element and the smallest part of ordinary matter. The element is made up of one type of atoms which consists of protons, electrons and neutrons are the subatomic particles. Examples of elements, carbon $\left( C \right),$ silicon $\left( Si \right),$ germanium $\left( Ge \right),$etc. A compound is made up of two or more elements which are different physical and chemical properties that elements present in the compound.
Examples: Silica $\left( Si{{O}_{2}} \right)$ , sodium chloride $\left( NaCl \right)$, some of the key points of elements are as follows as: The most fundamental substance with a single type of atom. Chemical reaction is not required and not all elements are not required.
Silicon dioxide is known as silica with the molecular formula $=Si{{O}_{2}}$ ​ which is a compound, not an element.
Diamond and graphite are purely made up of carbon i.e. $C,$ an element. Ozone is trioxygen molecule i.e. $O_3,$ an element.

So, the correct answer is Option C.

Note: Chemical composition is as mass and occupies some from space. Molecules are further divided into homo-atomic and hetero-atomic molecules. All compounds are molecules but not all molecules are compounds. Molecules exist with all properties of the elements or compounds.