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Q46 (CDS-I/2015) Science & Technology › Basic Science (Physics, Chemistry, Biology) › Applied everyday chemistry Answer Verified

Which one among the following is used in making lead pencils ?

Result
Your answer: —  Â·  Correct: B
Explanation

Pencil leads are primarily made of graphite, a naturally occurring crystalline form of carbon. Despite the name 'lead', elemental lead has never been used in modern pencils; the term originated because graphite was historically mistaken for lead ore, such as galena, due to its similar appearance. In the manufacturing process, graphite is finely ground and mixed with clay (kaolin) and binding agents to create the pencil core. The ratio of graphite to clay determines the hardness and darkness of the pencil: more graphite results in a softer, darker mark, while more clay makes it harder and lighter. Graphite's unique hexagonal layered structure allows the carbon atoms to slide over one another, making it an ideal material for smooth writing and drawing.

Sources

  1. [1] Science , class X (NCERT 2025 ed.) > Chapter 4: Carbon and its Compounds > Allotropes of carbon > p. 61
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