Two cups of the same size are filled to the brim with clear liquids. only one container holds water. the other contains a liquid that has greater density than water. how could you safely identify the container holding the water?

By weighing the two cups: the lighter cup will be the one holding the water.

Explanation:

Start from the density formula: density = mass / volume.

Since the two cups are of the same size and are filled to the brim, you know that the volumes of the two clear liquids are equal.

Then, being the volume a constant in the formula of density, the liquid that has greater density will have a higher mass.

So, when you weigh both containers, the one with the higher mass is containing the liquid with the greater density and the other one, with the lighter mass, is holding the water.

Talc (french chalk) is the ingredient

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.