Question

Which one of the following elements exists as a monatomic molecule?
A.Oxygen
B.Phosphorus
C.Sulphur
D.Argon

Answer 1

Hint: Let us first get familiar with what molecules. A molecule is a chemically bound group of two or more atoms that are electrically neutral. Molecules differ from ions in that they do not have an electrical charge.

Complete answer:
Now let us understand about different types of molecules:
Monoatomic molecule: A molecule that contains only one atom and lacking any covalent bonds. \[He,{\text{ }}Ne,{\text{ }}Ar,{\text{ }}Kr,{\text{ }}Xe,\] and \[Rn\]Rn are all monatomic noble gases.
Diatomic molecule: Diatomic molecules have only two atoms, which may be of the same or different chemical elements. The prefix di- comes from Greek and means "two." Examples: Oxygen, hydrogen, nitrogen.
Triatomic molecules: Triatomic elements are those that have three atoms in them. Example: Ozone
Polyatomic molecules: Polyatomic elements are those that have more than two atoms bound together by a covalent bond. Example: Sulphur

So option (D) is correct.

Note:
Ozone is triatomic because it contains three oxygen atoms, while phosphorus is tetratomic because it contains four atoms in its molecule. Molecules have a chemical formula that indicates the different types of atoms in the molecule and uses subscripts to indicate how many of each type of atom are present. Molecules come in a variety of sizes and shapes. You might have small molecules like carbon dioxide and molecules might be huge like hemoglobin. Molecules are found everywhere, from the air you breathe to the sugar that makes those cookies so delicious.