1. Electrons are present in the nucleus.   True   False   2. Isotopes have same atomic weight.   True   False   3. The number of electrons in a neutral atom is equal to its atomic number.   True   False   4. One atom of carbon and two atoms of oxygen combine to form a molecule of carbon dioxide [CO2].   True   False   5. Neutrons are negatively-charged.   True   False   6. The smallest atom is that of hydrogen.   True   False   7. Since an atom of the element sodium contains 11 protons and 12 neutrons, its atomic number is 23.   True   False