Which of the following statements is true about nonmetals?

Nonmetals are characterized by specific physical and chemical properties that distinguish them from metals. The correct statement highlights that nonmetals are usually brittle and poor conductors of heat and electricity. This distinction is important because it reflects the nature of nonmetals: they tend to have more varied physical forms, often existing as gases (like oxygen and nitrogen) or solids that are brittle (like sulfur and phosphorus) at room temperature. Unlike metals, which typically exhibit malleability and conductivity, nonmetals lack these properties and do not conduct heat or electricity well due to their atomic structure, which does not allow for the free movement of electrons.

The other statements do not accurately describe nonmetals. While some nonmetals can have high melting points, many do not, and there is considerable variation among nonmetals regarding their melting and boiling points. Additionally, while certain nonmetals are solid at room temperature, others exist in gaseous states; therefore, it is not accurate to say they are all solid. Lastly, nonmetals are generally not good conductors of heat, further reinforcing the validity of the chosen statement.