What are the characteristics of lead?

Lead is characterized as a gray metal that is toxic and heavy, which is accurately described by the correct choice. This heavy metal has a density that makes it much heavier than many common materials, contributing to its use in applications like batteries, shielding from radiation, and other industrial uses. The toxicity of lead is a significant concern, particularly regarding exposure to humans, as it can cause severe health issues, especially in children, including developmental delays and neurological damage.

In contrast, the other options do not accurately depict lead's properties. While lead does possess some conductivity, it is not known for being a strong conductor of electricity compared to metals like copper or aluminum. It is not known for being lightweight or malleable relative to other metals; although it is malleable, it is too dense to be classified as lightweight. Lastly, lead is neither transparent nor brittle; instead, it is opaque and relatively soft, which is different from materials that are known for their brittleness. This understanding underscores the critical characteristics of lead and highlights its relevance to health and safety regulations.