If Kr (#36) goes through beta decay,
which particle is given off along with a
beta particle

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.

Wow that a lot of text for my tiny so i no wanna answer

Answer the molar mass of magnesium is 24.305g/mol.

The answer is a. that is an exothermic reaction which means it produces heat