Which of the following is a highly corrosive salt?

HgCl₂

The correct answer is option 2. HgCl₂.

Mercury(II) chloride \((HgCl_2)\), also known as mercuric chloride or corrosive sublimate, is a highly corrosive salt due to its chemical properties and interactions with other substances. Here's an explanation of why mercury(II) chloride is highly corrosive:

Chemical Reactivity: Mercury(II) chloride is highly reactive with a wide range of substances, including metals, organic compounds, and biological tissues. It readily reacts with metals to form metal chlorides, which can corrode the metal surfaces. This reactivity is due to the strong electronegativity of chlorine and the tendency of mercury to form stable complexes with other elements.

Solubility: Mercury(II) chloride is soluble in water, which allows it to easily penetrate and corrode materials upon contact. Once dissolved in water, it can form acidic solutions that enhance its corrosive properties. These solutions can cause severe damage to metals, plastics, and biological tissues.

Toxicity: Mercury(II) chloride is highly toxic to both humans and animals. Exposure to mercury(II) chloride can lead to acute poisoning and severe health effects, including damage to the respiratory, nervous, and renal systems. The corrosive nature of mercury(II) chloride compounds exacerbates their toxic effects when they come into contact with living tissues.

Historical Uses: Historically, mercury(II) chloride has been used as a disinfectant, fungicide, and pesticide due to its strong antimicrobial properties. However, its use has declined significantly due to concerns about its toxicity and environmental impact. Nevertheless, its corrosive properties make it effective for certain industrial and laboratory applications where corrosive substances are required.

In summary, mercury(II) chloride is highly corrosive due to its chemical reactivity, solubility, toxicity, and historical uses. Its ability to react with metals, form acidic solutions, and penetrate biological tissues makes it a potent corrosive agent that requires careful handling and disposal to prevent harm to both human health and the environment.