Common uses of arsenic?

• A. Pharmaceuticals, cosmetics, textiles
• B. Fertilizers, plastics, paints
• C. Pesticides, wood preservatives, semiconductors
• D. Food additives

Answer: (C)

Arsenic has multiple uses that come from its strong biological activity and its chemical behavior in different forms. The most common, widely recognized applications are in pesticides, wood preservatives, and semiconductors.

In pesticides, arsenic compounds have long been valued for their toxicity to a range of pests. Inorganic arsenicals and organoarsenicals can disrupt essential biological processes in insects and other pests, making them effective controls in agriculture and stored products. This pest-killing property is why arsenic-containing pesticides became popular in the past.

As a wood preservative, arsenic compounds protect timber from decay and insect attack. Historically, formulations containing arsenic were used to deter fungi and termites, helping wood last longer in structural and outdoor applications. The durability and protective effects make these arsenic-based preservatives a notable use, even though their environmental and health risks are now tightly regulated.

In semiconductors, arsenic plays a crucial role as a dopant to tailor electrical properties. By introducing arsenic into semiconductor materials, manufacturers can create n-type regions, which are essential for devices like diodes and transistors. Arsenic is also a core component of certain compound semiconductors (such as gallium arsenide, GaAs) used in high-speed electronics and optoelectronics.

Other potential uses, such as in some cosmetics, textiles, or food-related products, either were historical or are not common today due to toxicity and regulatory limits. Arsenic’s strong toxicity drives stringent safety standards and restricted, carefully controlled applications, which is why the trio of pesticides, wood preservatives, and semiconductors stands out as the typical, widely recognized uses.