A common isotope of iron (Fe) has an atomic number of 26 and a mass number
of 56. The total number of subatomic particles in the nucleus is: *
26

82

Explanation:

Atomic number of the isotope is 26 and it has a mass number of 56

X = ⁵⁶₂₆Fe

The three main subatomic particles in an atom are

1. Proton

2. Neutron

3. Electron

The number of protons and electrons are usually equal so as to maintain electrical neutrality in the atom except in cases where it's a charged particles hence the number of proton and electrons will differ.

In this case, the atomic number is 26 and atomic numbers are also known as the number of protons (positively charged particle).

Proton = 26

Electrons = 26 (since it's a naturally charged particle)

Neutron = ?

Mass number = sum of proton and neutrons. This variation in the mass number usually leads to isotopes of an atom and this is mainly caused by variation in the number of neutrons eg. Carbon-12 and Carbon-13 have different number of neutrons.

Mass number = protons + neutrons

Neutrons = mass number - protons

Neutrons = 56 - 26

Neutrons = 30

Subatomic particles present are

Protons = 26

Electrons = 26

Neutrons = 30

Total number = (26 + 26 + 30) = 82

The total number of subatomic particles is 82.