Disinfective action of chlorine is due to which of the following?
**Core Concept:** Chlorine is a chemical compound with the formula Cl2, which is commonly used as a disinfectant due to its antimicrobial properties. The disinfective action of chlorine is based on its ability to inactivate microorganisms by damaging cellular components, leading to cell death.
**Why the Correct Answer is Right:**
The correct answer is **C. Chlorine is a halogen gas that reacts with water (H2O) to form hypochlorous acid (HClO) and hydrochloric acid (HCl).** Hypochlorous acid is the active agent responsible for the disinfective action of chlorine.
**Why Each Wrong Option is Incorrect:**
A. **Option A: Chloramine (NH2Cl)**: Chloramine is formed when chlorine combines with ammonia (NH3) and is not the active agent responsible for the antimicrobial properties of chlorine.
B. **Option B: Hydrogen peroxide (H2O2)**: Hydrogen peroxide is a different compound that is not involved in the disinfective action of chlorine.
D. **Option D: Hypochlorous acid (HClO)**: Although hypochlorous acid is formed when chlorine reacts with water, it is not the active agent responsible for the disinfective action of chlorine.
**Clinical Pearl/High-Yield Fact:** Hypochlorous acid has a short half-life (around 5 minutes) and is quickly converted into chloramine and chlorite ions (ClO2) through the action of myeloperoxidase enzyme present in neutrophils. This reaction explains why chlorine-based disinfectants are typically used as a mixture of hypochlorous acid and chloramine, which ensures a sustained antimicrobial effect.
In summary, the correct answer is C, as hypochlorous acid (HClO) is the active agent responsible for the disinfective action of chlorine. The other options are incorrect due to their lack of involvement in the formation of hypochlorous acid or due to being incorrectly identified as the active agent. Hypochlorous acid is formed when chlorine reacts with water and is quickly converted into chloramine and chlorite ions, which explains the use of chlorine-based disinfectants as a mixture of hypochlorous acid and chloramine.