The true statement concerning the atomic nucleus is:
It contains protons, neutrons, and electrons.
It takes up most of the volume of the atom.
It contains most of the mass of the atom.
It is made up of electrons only.

It contains most of the mass of the atom.

Explanation:

The nucleus of an atom contains the protons and neutrons. The electrons revolve around the nucleus and they have very small masses ( the mass of an electron is about 9.1x10^-31kg) when compared with the mass of the protons and neutrons. The nucleus is the massive part of an atom.

if the thermos has a vacuum innner, then heat through conv currents and conduction are reduced = vacuum flask

an electric circuit