B

A chemical element in the periodic table that has the atomic number 5. A trivalent metalloid element, boron occurs abundantly in the ore borax. There are several allotropes of boron; amorphous boron is a brown powder, but metallic boron is black. The metallic form is hard (9.3 on Mohs' scale) and a poor conductor at room temperature. It is never found free in nature. Crystalline boron exists in many polymorphs.

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