A 67.0 mL aliquot of a 0.400 M stock solution must be diluted to 0.100 M. Assuming the volumes are additive, how much water should be added?

If you explain it more through i will answer it : )

Ido not understand. 

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.