Question

Which of the following is a monatomic molecule?
A.${{{H}}_{{2}}}$
B.${{C}}{{{l}}_{{2}}}$
C.$[{{C}}{{{O}}_{{2}}}]$
D.Both A and B

Answer 1

In this question, we have to identify the homoatomic molecules. Molecules whose atoms are made up of the same elements are monatomic molecules. A monatomic molecule is also called a diatomic molecule. It has a molecular formula ${M_2}$. It can also be homoatomic- trivalent like ${{{O}}_{{3}}}$.

Complete step by step answer:
-We will discuss the term molecule, and its types i.e. homoatomic and heteroatomic.
-Now, we will define a molecule. We can say that when a group of atoms is bonded together, it is termed as a molecule.
-As mentioned, a molecule is divided further into two types, i.e. homoatomic and heteroatomic.
-First, let us talk about the term homoatomic molecules.
-As we know, the term homo means ‘same’, a molecule is called homoatomic when the atoms in a molecule are made up of the same elements.
-Second, we have heteroatomic molecules. We can define it as when the molecule is made up of different elements like water (${{{H}}_{{2}}}{{O}}$)
-Now, on consideration with the options A, B, C, and D.
-First, we have option A i.e. ${{{H}}_{{2}}}$, we can see that it is made up of two atoms of hydrogen. So, it is a monatomic molecule.

-Similarly, option B is ${{C}}{{{l}}_{{2}}}$ in which both the atoms have the same element Chlorine. So, we can say that it is a monatomic molecule.
-In the last, we can conclude that ${{{H}}_{{2}}}$ and ${{C}}{{{l}}_{{2}}}$ are homoatomic molecules.
Hence, the correct option is D, i.e. both A and B.

Note:
In option C, ${{C}}{{{O}}_{{2}}}$,we can see that it consists of 2 atoms of oxygen and one atom of carbon. Thus, it is a heteroatomic molecule. A molecule is called heteroatomic when the elements that constitute the molecule are different. Heteroatomic molecules are polyatomic molecules. Hetero means “different”.