Question

question 1-27
which particles make up most of the mass of an atom?
○ protons and neutrons
○ protons and electrons
○ neutrons and molecules
○ electrons and molecules

Explanation:

To determine which particles make up most of an atom's mass, we recall atomic structure: the nucleus contains protons and neutrons, which have significant mass, while electrons have negligible mass. Molecules are not part of an atom's internal structure. So protons and neutrons contribute most to an atom's mass.

Answer:

A. protons and neutrons