Question

Which of the following is not an element?
(A) Graphite
(B) Germanium
(C) Silica
(D) Silicon

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 solution:
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 (C), silicon (Si), germanium (Ge), 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 $Si{{O}_{2}},$ sodium chloride NaCl, Ozone ${{O}_{3}}$
There are some difference between element and molecule based on their properties given below table

Comparison	Molecule	Elements
Definition	Atoms which bond together with other atoms to form a molecule	The most fundamental substance with a single type of atom
Chemical reaction	Required	Not required
Size	Large	Small
Compounds	All compounds are molecules	Not all are compounds

From the above discussion, silicon (Si), germanium (Ge) are elements. Graphite is an allotropy of carbon elements. So, silica $Si{{O}_{2}},$is not an element.

Hence, 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.