In the following compound (NaCl), can you please tell me the following: Is it an ionic or covalent compound?
How many valence electrons does Na have?
How many valence electrons does Chlorine have?
How many electrons are gained and lost by each atom

You would be correct, boiling water does disinfect contamination.    the property of disinfecting means to kill  germs, bacteria and other pathogens or contamination  that might cause an infection or cause a person to become sickly. a couple methods of disinfecting are using soap, other cleaning supplies or by simply "boiling" the contaminate.  the reason why boiling water disinfects certain attributes is because some cells cannot survive the heat and pressure.