Atomic mass of an element is equal to the sum of number of

electrons and protons only

protons and neutrons only

electrons and neutrons only

electrons, protons and neutrons

Answer is Right!

Answer is Wrong!

This question was previously asked in

UPSC NDA-2 – 2020

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The correct answer is (B) protons and neutrons only. The atomic mass of an element (more accurately, the mass number of a specific isotope or the relative atomic mass) is primarily determined by the mass of the particles in the nucleus. Protons and neutrons are located in the nucleus and account for almost all of an atom’s mass. The mass of electrons is negligible in comparison.

The nucleus of an atom contains protons and neutrons, which contribute significantly to its mass. Electrons have very little mass.

The Mass Number (A) of an isotope is the sum of the number of protons (Z) and neutrons (N) in its nucleus (A = Z + N). The atomic mass listed on the periodic table for an element is the weighted average of the masses of its naturally occurring isotopes, taking into account their relative abundances.

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