What harmful gas is released when mixing ammonia and bleach?

When mixing ammonia and bleach, the harmful gas that is released is chlorine gas. This occurs because bleach, which typically contains sodium hypochlorite, reacts with ammonia to produce this toxic gas. Chlorine gas is particularly dangerous; it can cause respiratory distress, irritation to the eyes and throat, and at higher concentrations can be fatal.

Understanding the chemical interaction between ammonia and bleach is critical in the context of safety and hazard management, particularly for individuals working in environments where such substances may be present. The other gases listed, while harmful in different contexts, are not produced from the reaction of ammonia and bleach. Therefore, recognizing chlorine gas as the correct answer reinforces the importance of not mixing certain cleaning agents to prevent harmful exposure.