How do scientists determine the number of neutrons in an isotope of an atom?
o
they add the number of protons and electrons.
o
they subtract the number of protons and neutrons from the mass number
o
they subtract the number of protons from the mass number
o
they subtract the number of electrons from the mass number

Option (c) is the correct answer.

Explanation:

Isotopes are the species that contain same number of protons but different number of neutrons.

For example, isotopes of carbon are and .

So, both these atoms contain six protons but different number of neutrons.

As sum of total number of protons and neutrons present within an element is known as atomic mass.

Hence, number of neutrons can be calculated as follows.

                      Atomic mass = atomic number + no. of neutrons

                  No. of neutrons = atomic mass - atomic number

Thus, we can conclude that scientists determine the number of neutrons in an isotope of an atom as they subtract the number of protons from the mass number.