Question

The mass number A of an atom is equal to the$\mathrm{\_\_\_\_\_\_\_\_\_\_\_\_}$

• A. Number of electrons
• B. Number of neutrons $+$ electrons
• C. Number of protons $+$ neutrons
• D. Number of protons $+$ electrons

Answer 1

The correct option is C

Number of protons $+$ neutrons

Explanation for correct option:

(C) Number of protons $+$ neutrons

• The mass number of an element is determined by the number of protons and neutrons.
• Mass number = protons $+$ neutrons.

Hence, the correct option is (C).

Explanation for incorrect options:

Mass number includes total protons and total neutrons present in an atom of an element. Mass number does not include number of electrons. Therefore, options (A), (B) and (D) stand incorrect.

Hence, the correct option is (C), Number of protons $+$ neutrons