International General Certificate of Secondary Education (IGCSE) Chemistry Practice Exam

Graphite can be used in pencils as a writing material primarily because it can easily break apart into layers. This characteristic is due to the unique structure of graphite, which consists of carbon atoms arranged in a two-dimensional planar format. Each layer is held together by weak van der Waals forces, allowing the layers to slide over one another easily. When you write with a pencil, these layers are scraped off and leave marks on the paper.

The high melting point of graphite is a property related to its stability and does not contribute to its function as a writing material. The assertion that graphite is a liquid at room temperature is incorrect; graphite is solid. Lastly, while graphite does conduct electricity and can have charge carriers, it does not contain positively charged ions in a manner relevant to its use in pencils. The ability to break apart into layers is the defining feature that gives graphite its utility in writing instruments.