Question

How many stable isotopes does oxygen have\[?\]
A) One
B) Two
C) Three
D) Four

Answer 1

Hint: Stable isotopes of a particular element are the ones which are non-radioactive in nature and hence do not undergo radioactive decay spontaneously. Consider the different isotopes of oxygen that are available in nature and try to find out which ones are stable and hence find the count of the total number of stable isotopes of oxygen.

Complete step-by-step answer:
Isotopes are variants of a particular chemical element with the same atomic number and position in the periodic table and nearly identical chemical behaviour but with different atomic masses and physical properties. Stable isotopes of a particular element are the ones which are non-radioactive in nature and hence do not undergo radioactive decay spontaneously.
For oxygen various isotopes can be found ragging from $^{11}O$ to $^{26}O$ out of which $^{16}O{,^{17}}O$and $^{18}O$are stable isotopes of oxygen while others are radioactive in nature.
So oxygen has three stable isotopes.

Additional Information:
The relative abundance of $^{16}O$ is high because it is the primary isotope of oxygen being the principal product of stellar evolution. Most of the $^{16}O$ isotope is synthesized at the end of the helium fusion process in stars. $^{17}O{,^{18}}O$are secondary isotopes of oxygen, $^{17}O$ is primarily made by the burning of hydrogen into helium during the $CNO$ cycle while $^{18}O$ is produced when $^{14}N$ captures one helium nucleus to form $^{18}F$ which further decays to form $^{18}O$.

Hence the correct answer is option ‘C’.

Note: Do not confuse between isotopes and isobars as they are widely different from one another. Isotopes are variants of a particular chemical element that contain equal numbers of protons but different numbers of neutrons in their nuclei, and hence differ in relative atomic mass but not in chemical properties. Example: $_1{H^1}{,_1}{H^2}{,_1}{H^3}$. Isobars are atoms of different chemical elements that have the same mass number but differ in atomic number. Example:$^{40}S{,^{40}}Cl{,^{40}}Ar$.