Question

Oxygen $\left( {{O_2}} \right)$ and ozone $\left( {{O_3}} \right)$ are:
A: Allotropes
B: Isotopes
C: Isomers
D: Isobars

Answer 1

Allotropy is the property of a chemical element or compound due to which it is able to exist in two or more different forms. These different forms are of the same state. In the allotropic forms, atoms are bound in a different manner from other forms.

Complete step by step answer:
Allotropy is the property of a chemical element or compound due to which it is able to exist in two or more different forms. These forms exist in the same state. These forms differ from each other in the arrangement of their atoms or molecules.
Isotopes are the atoms of the same element which have the same atomic number but different mass number. These atoms have different numbers of neutrons in their nucleus due to which their atomic number remains the same but mass number differs.
Isomers are the molecules, which have the same molecular formula but their arrangement of atoms is different. There exist many types of isomers. Isomers have the same chemical formula but the chemical formula of oxygen and ozone is different. Therefore, these are not isomers.
Isobars are the atoms of different elements which have different atomic numbers but same mass number. These atoms have different numbers of protons in their nucleus. Due to which their atomic number varies.
Isotopes and isobars represent comparison of two atoms of the same and different elements respectively. But oxygen and ozone are molecules. Therefore, isotope and isobar is not the answer. Isomers are species with the same chemical formula and different structure. But oxygen and ozone have different chemical formulas. This means, isomers is also not the answer. So, the correct answer is allotropes. As allotropy is the property of a compound due to which it can exist in more than one form. Oxygen and ozone are allotropes but diatomic oxygen $\left( {{O_2}} \right)$ is more common.
Therefore the correct answer is option A.

Note:
Ozone is a highly reactive gas which is composed of three oxygen atoms. It is present in earth’s upper atmosphere (stratosphere) and lower atmosphere (troposphere). It is both a natural and manmade product.