1. Isotopes have similar chemical properties.   True   False   2. Electrons are present in the nucleus.   True   False   3. One atom of carbon and two atoms of oxygen combine to form a molecule of carbon dioxide [CO2].   True   False   4. In a neutral atom, the number of electrons and protons is equal.   True   False   5. Of a proton, neutron and an electron, the electron is the lightest.   True   False   6. In a neutral atom, the number of neutrons and protons is equal.   True   False   7. Hydrogen and oxygen are combined chemically in a fixed proportion of 2:1 in the compound water.   True   False