1. Isotopes differ in the number of neutrons they have in their nucleus.   True   False   2. The number of electrons in a neutral atom is equal to its atomic number.   True   False   3. In a neutral atom, the number of neutrons and protons is equal.   True   False   4. Hydrogen and oxygen are combined chemically in a fixed proportion of 2:1 in the compound water.   True   False   5. Isotopes have similar chemical properties.   True   False   6. Isotopes have same atomic number.   True   False   7. Neutrons are negatively-charged.   True   False