In the context of calcium hypochlorite tablets used for disinfection, what does 65.0% refer to?

• A. The percentage of the tablet's mass that is available chlorine.
• B. The percentage of chlorine gas produced by the tablet.
• C. The percentage of the tablet's weight that is calcium compound.
• D. The percentage of water that dissolves the tablet.

Answer: (A)

The main idea here is available chlorine content. For calcium hypochlorite tablets, the percentage shown indicates how much of the tablet’s mass can act as chlorine when the tablet is dissolved in water. That chlorine is what provides disinfection by forming hypochlorite species in solution. So 65.0% means about 0.65 grams of chlorine-equivalent are contained in each gram of tablet, with the remaining mass made up of other components like moisture, binders, and inert material. It’s not about chlorine gas production or about calcium content, and it doesn’t describe how quickly the tablet dissolves in water.