Question

Choose the correct answer. The difference between the mass number of an isotope and its atomic number is (a) directly related to the identity of the element: (b) the number of electrons: (c) the number of neutrons; (d) the number of isotopes.

Answer 1

Answer : The correct answer is, (c) the number of neutrons

Explanation :

Isotope : It is defined as the element that have the same number of protons but have the different number of neutrons of each of the atom.

Atomic number is defined as the number of protons or number of electrons.

Atomic number = number of protons = number of electrons

Mass number is defined as the sum of number of protons and number of neutrons.

Number of neutrons = Mass number - Atomic number

For example : For Carbon - 13 isotope.

Mass number = 13

Atomic number = 6

Number of neutrons = Mass number - Atomic number

Number of neutrons = 13 - 6 = 7

Hence, the difference between the mass number of an isotope and its atomic number is the number of neutrons.