Final answer:
Chlorine can be utilized in all the given forms: as a gas for disinfection in water treatment, as a liquid in the form of bleach, and as a powder like calcium hypochlorite for various cleaning and disinfecting purposes.
Step-by-step explanation:
Chlorine can be used in various forms for different applications. These forms include chlorine gas, which is a pale yellow-green gas used for water and wastewater treatment. It combines with water to produce hypochlorous acid, an effective disinfectant. Chlorine is also available in liquid form, commonly known as liquid bleach or sodium hypochlorite, which is widely used as a disinfectant and a bleaching agent. Furthermore, chlorine can be found in powder form in products such as calcium hypochlorite, which is often referred to as "bleaching powder" and used for disinfecting surfaces and in swimming pools. Therefore, the correct answer to the question is D) All of the above, meaning chlorine can be used as a gas, a liquid, and a powder.