Final answer:
The main active ingredient in bleach is sodium hypochlorite (NaOCl), which releases chlorine.
Step-by-step explanation:
The main active ingredient in common household bleach, also known as chlorine bleach, is sodium hypochlorite (NaOCl).
Sodium hypochlorite is a pale greenish-yellow dilute solution commonly used as a disinfectant or bleaching agent.
When sodium hypochlorite is dissolved in water, it easily decomposes, liberating chlorine, which is the active agent in bleach.