1. The atom is mainly empty.   True   False   2. The number of electrons in a neutral atom is equal to its atomic number.   True   False   3. An element is a substance made up of different kinds of atoms.   True   False   4. Of a proton, neutron and an electron, the electron is the lightest.   True   False   5. In a neutral atom, the number of neutrons and protons is equal.   True   False   6. Neutrons are negatively-charged.   True   False   7. One atom of carbon and two atoms of oxygen combine to form a molecule of carbon dioxide [CO2].   True   False