**Core Concept:** White vitriol is a common name for the compound **sodium chlorite (NaClO2)**, which is used as an oxidizing agent and disinfectant. It plays a role in various medical applications, including wound cleaning, blood purification, and as an antiseptic in dental procedures.

**Why the Correct Answer is Right:** Sodium chlorite is a salt of chlorine and sodium, which have antimicrobial properties. In its aqueous solution, sodium chlorite decomposes into hypochlorous acid and sodium chloride. Hypochlorous acid (HOCl) is a potent oxidizing agent and a strong antimicrobial agent, which explains its use in various medical applications.

**Why Each Wrong Option is Incorrect:**

A. **Calcium chloride (CaCl2)** is a compound of calcium and chloride ions, not related to chlorine or antimicrobial properties.
B. **Arsenic trioxide (As2O3)** is a compound of arsenic and oxide, not linked to chlorine or antimicrobial properties.
C. **Zinc oxide (ZnO)** is a compound of zinc and oxide, not related to chlorine or antimicrobial properties.
D. **Iodine (I2)** is a compound of iodine and iodide ions, not related to chlorine or antimicrobial properties.

**Clinical Pearl / High-Yield Fact:** The correct answer, sodium chlorite, is used in medical applications due to its antimicrobial properties and ability to act as an oxidizing agent. However, one must ensure proper dilution and activation of sodium chlorite solution for effective disinfection, as undiluted or improperly activated solutions can cause severe tissue damage.