Question

Identify the correct statements.
(i) Atomic number = number of protons + number of electrons
(ii) Mass number = number of protons + number of neutrons
(iii) Atomic mass = number of protons = number of neutrons
(iv) Atomic number = number of protons = number of electrons

• A. (i) and (ii)
• B. (i) and (iii)
• C. (ii) and (iii)
• D. (ii) and (iv)

Answer 1

The correct option is D (ii) and (iv)

The atomic number of an element is the number of protons (positive charge) which is also equal to the number of electrons (negative charge) as the atom is always electrically neutral.

Since the mass of an atom is concentrated in the nucleus of the atom, its mass number is the total number of sub-atomic particles which are present in the nucleus. Protons and neutrons together are called nucleons.