Question

Identify the element if it has mass number 14 and 8 neutrons.
(A) Isotope of oxygen
(B) Isobar of oxygen
(C) Isotope of carbon
(D) Isobar of carbon

Answer 1

Before solving this question it is important to know the basic terms such as atomic number, mass number, isotopes, isobars, neutrons, protons, electrons etc. There are two stable isotopes of carbon and there are three stable isotopes of oxygen.

Complete step by step solution:
Let’s understand the basic terminology:
Electrons, protons and neutrons are the subatomic particles. Electrons are the subatomic particle which carries a negative charge, while protons are the subatomic particles with a positive charge and neutrons are the subatomic particle which has no charge. Protons and neutrons both are present in the nucleus of the atom whereas electrons revolve around the nucleus.
The atomic number is the number of protons present in the nucleus of every atom of that element.
The mass number is the sum of protons and neutrons present in the nucleus of the atom. Protons and neutrons are collectively known as nucleons.
Isotopes are the atoms of the elements which have the same atomic number but a different mass number.
Isobars are the atoms of the element having the same mass number but a different atomic number.
Now given in the question mass number is 14 and the number of neutrons is 8.
We can calculate the number of protons by subtracting the number of neutrons from the mass number,
Number of protons = $14-8=6$
And the number of protons in the atomic number, the element with atomic number 6 is carbon.

Hence the correct answer is option (C) same atomic number but different mass number i.e. isotope of carbon.

Note: The stable isotopes of carbon is ${{C}^{12}}\text{ and }{{\text{C}}^{13}}$. There is one more isotope of carbon but it is radioactive i.e. ${{C}^{14}}$. The stable isotopes of oxygen are ${{O}^{18}},{{O}^{17}}\text{ and }{{O}^{16}}$. Radioactivity means emission of ionizing radiations or particles.