2. Which of these is generally a property of substances held together by metallic bonding? high boiling points poor conductors of electricity rigid and brittle low melting points

Substances held together by metallic bonding generally have high boiling points. This is because metallic bonds involve a lattice of positive metal ions surrounded by a "sea" of delocalized electrons, which allows for strong attractions between the ions and electrons. These strong interactions require significant energy to break, resulting in high melting and boiling points. Additionally, substances with metallic bonding are typically good conductors of electricity due to the mobility of the delocalized electrons. They are also malleable and ductile rather than rigid and brittle.