1.00 l sample of polluted water was analysed for lead(II) ions, , by adding an excess of sodium sulfate to it. The mass of lead(II) sulfate
that precipitated out was 229.8 mg. Calculate the concentration of lead
(II) ions in mg l -1 present in the initial sample of polluted water.

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.