Which contains more molecules; a mole of chlorine gas (cl2 ) or a mole of glucose (c6h1206) ?

This is a tricky question. a mole of any compound contains the same number of molecules of that certain compound. so, one mole of chlorine gas has the same number of molecules as one mole of glucose, which is 6.02 x 10^23.

this is avogadro's number and it applies for any mole of molecules. 

the question is tricky because it is like asking. " what weighs more, a pound of feathers or a pound of rocks?" the both weigh the same, a pound. when ewe talking about moles, same as pounds, it is a quantity unit. one mole will aways be equal to 6.02 x 10^23 molecules.

16- counting by fours

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.