Question

which is a characteristic of the part of the atom marked \a\? it contains most of the mass. it is negatively charged. it is mostly empty space. it is composed of electrons.

Explanation:

In an atom, the nucleus contains most of the mass as it is made up of protons and neutrons which have significant mass compared to electrons. Electrons are negatively - charged and are in the electron - cloud outside the nucleus. The electron - cloud is mostly empty space. If "A" is the nucleus, it contains most of the mass.

Answer:

It contains most of the mass.