The most poisonous Mercury salt is:
**Core Concept**
Mercury salts, also known as mercurials, are a group of compounds derived from mercury that have been used historically in various medical applications, including as antiseptics, antifungals, and anti-inflammatory agents. However, due to their toxicity, their use has largely been phased out in modern medicine. The toxicity of mercury salts varies depending on their chemical properties.
**Why the Correct Answer is Right**
The correct answer is **Mercuric Chloride**. Mercuric chloride (HgCl2) is a highly toxic mercury salt that has been used as an antiseptic and antifungal agent. It is particularly toxic because it can easily cross the blood-brain barrier and cause severe neurological damage. Mercuric chloride's toxicity is due to its ability to bind to sulfhydryl groups in proteins, disrupting cellular function and leading to cell death.
**Why Each Wrong Option is Incorrect**
**Option A:** Mercuric Sulfide is less toxic than Mercuric Chloride and is used in some dental applications.
**Option B:** Mercurous Chloride is also known as Calomel and is less toxic than Mercuric Chloride.
**Option C:** Phenylmercuric Nitrate is a mercury salt used as a preservative in some vaccines, but it is not the most toxic mercury salt.
**Clinical Pearl / High-Yield Fact**
Mercury salts, particularly Mercuric Chloride, can cause severe kidney damage and nephrotic syndrome, making them a significant health risk if mishandled or misused.
**Correct Answer:** C. Mercuric Sulfide