**Core Concept**
Bleaching powder, chemically known as calcium hypochlorite (Ca(OCl)2), is a disinfectant widely used in various industries, including water treatment and healthcare. Its effectiveness lies in its ability to release hypochlorous acid (HOCl), a potent antimicrobial agent.

**Why the Correct Answer is Right**
Bleaching powder releases hypochlorous acid (HOCl) when dissolved in water, which then kills bacteria, viruses, and fungi through oxidation of their cellular components. The hypochlorous acid also disrupts the bacterial cell membrane, leading to cell lysis and death. This process is facilitated by the presence of calcium and chlorine ions in the solution.

**Why Each Wrong Option is Incorrect**
**Option A:** This statement is true for bleaching powder, as it is indeed used as a disinfectant in hospitals and healthcare settings to reduce the spread of infections.
**Option B:** This statement is also true, as bleaching powder is commonly used in swimming pools to maintain a clean and safe environment for users.
**Option C:** This statement is incorrect, as bleaching powder is not typically used as a tooth whitening agent. Instead, it is used for disinfecting surfaces and water.

**Clinical Pearl / High-Yield Fact**
It's essential to handle bleaching powder with caution, as it can cause severe skin and eye irritation. Wearing protective gloves and eyewear is crucial when handling this chemical.

**Correct Answer: C. Bleaching powder is not typically used as a tooth whitening agent.**