What volume of water would you add to 15.0 ml of 12 m hcl to make it to 6.0 m solution?

They are like other investigations? say there was a murder u have to do blood test and finger prints which run through a lab. 

12 is probably the typical age for a first kiss but i think its to young.

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.