1. Of a proton, neutron and an electron, the electron is the lightest.   True   False   2. Electrons revolve around the nucleus in shells or orbits.   True   False   3. Hydrogen and oxygen are combined chemically in a fixed proportion of 2:1 in the compound water.   True   False   4. Nucleus always contains a neutron.   True   False   5. Isotopes have same atomic weight.   True   False   6. One atom of carbon and two atoms of oxygen combine to form a molecule of carbon dioxide [CO2].   True   False   7. In a neutral atom, the number of neutrons and protons is equal.   True   False