Question

the majority of the mass of the atom is located in the ________. a nucleus b core electrons c pions and quarks d valence electrons

Explanation:

Atoms consist of a nucleus containing protons and neutrons, which have significant mass compared to electrons. Core and valence electrons have much less mass. Pions and quarks are sub - nuclear particles not directly related to the main mass location in an atom. The nucleus holds most of the atom's mass.

Answer:

A. nucleus