Question

the nucleus of an atom is a very small, dense region that contains over 99.9% of the atomic mass.
true
false

Explanation:

The nucleus of an atom is indeed a very small, dense region. It contains protons and neutrons, which are much more massive than electrons. Electrons are located outside the nucleus. Since protons and neutrons account for most of the atomic mass, the nucleus contains over 99.9% of the atomic mass.

Answer:

True