Elaborate on the classification of boron. a) boron is a noble gas and has a full valence electron shell, is chemically non-reactive, colorless, odorless, and low boiling point. b) boron is a metal and is shiny, malleable, ductile, conducts heat and electricity, forms basic oxides, and forms cations in aqueous solution. c) boron is a nonmetal and is dull, brittle, poor conductor of heat and electricity, forms acidic oxides, and forms anions in aqueous solution. d) boron is a metalloid and has properties of both metals and nonmetals - it appears dull but is ductile and forms both basic and acidic oxides.