Answer:
-Pencil where first used in 1795.
-A soft black lustrous form of carbon that conducts electricity and use as lead in a pencil and electrolyte anodes, as a lubricant, and as a moderator in nuclear reaction.
- HB pencil is a types of pencil where h stands for hard and B stands for black which
means hard black pencil .
-When h# is increased the pencil will be harder.