What is arsenic?

• A. A metalloid that is non-toxic
• B. A toxic metalloid found naturally in the environment
• C. A noble gas used in lighting
• D. A synthetic polymer used in plastics

Answer: (B)

Arsenic is a toxic metalloid that occurs naturally in the Earth’s crust and in groundwater in many regions. The key idea here is that arsenic is a metalloid, meaning it has properties between those of metals and nonmetals, and its most important feature for this question is its toxicity and natural occurrence. It isn’t non-toxic; it’s well known for health hazards at low exposure levels and is regulated in many environments because of cancer risk and other health effects. It isn’t a noble gas, which are inert atmospherically colored gases like helium or neon, nor is it a synthetic polymer used in plastics. In short, arsenic is a naturally occurring, toxic metalloid, not a gas or a synthetic material.