Which of the following is a key characteristic of calcium hypochlorite?

A key characteristic of calcium hypochlorite is that it forms a powder. This compound is typically encountered in a dry, powdered form, which makes it easy to handle and store. Its solid state allows for convenient application in water treatment processes, where it can be reliably used as a disinfectant due to its chlorine content.

In contrast, calcium hypochlorite is not highly soluble in water, which means that it does not dissolve easily, instead releasing chlorine in a controlled manner when added to water. It is also not a gas at room temperature; in fact, it exists as a solid. Furthermore, it tends to be unstable in humid conditions, which can lead to degradation and loss of effectiveness over time. Thus, the characteristic of forming a powder best describes calcium hypochlorite and its practical use in various applications, particularly in swimming pool sanitation and water disinfection.