Type of Carbon Often Used as a Pencil Lead
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Question is: Type of Carbon Often Used as a Pencil Lead
and the answer is: GRAPHITE
Word Meaning:
GRAPHITE — An allotrope of carbon, consisting of planes of carbon atoms arranged in hexagonal arrays with the planes stacked loosely, that is used as a dry lubricant, in "lead" pencils, and as a moderator in some nuclear reactors.
Definition source: Wiktionary (CC BY-SA 4.0)