How many calcium (ca) atoms are in the chemical formula:
caco3
1
5
3
none

There is one calcium, one carbon atom, and three oxygen atoms. Therefore, there are 5 atoms in CaCo3

Although the diagram is not shown, i know that the convection is heated by a the core.

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.