Final answer:
Safe drinking water as determined by the EPA should have a pH within specified limits. Additionally, chemical parameters like density and molarity are important for characterizing substances like aluminum, osmium, and solutes in solutions.
Step-by-step explanation:
The Environmental Protection Agency (EPA) guidelines state that safe drinking water should have certain chemical parameters within specified limits.
Among the options provided, pH is the correct answer. The pH of drinking water is critical because water that is too acidic or too basic can be harmful to human health and can also corrode pipes, potentially releasing harmful materials into the water.
Additionally, discussing other properties and measurements common in chemistry, the density of a substance, like aluminum or osmium, is its mass per unit volume. Molarity refers to the number of moles of a solute per liter of solution, which is a key concept when determining the concentration of substances in solutions, such as mercury in water or ethanol in a solution.