2018 · Q26
Which one of the following is not true for the form of carbon known as diamond ?
General KnowledgeChemistry
- AIt is harder than graphite.
- BIt contains the same percentage of carbon as graphite.
- CIt is a better electric conductor than graphite.
- DIt has different carbon to carbon distance in all directions.
Explanation
Diamond and graphite are both pure carbon, so they contain the same percentage of carbon, and diamond is indeed harder than graphite. However, diamond is an electrical insulator because all its valence electrons are locked in tetrahedral covalent bonds, whereas graphite conducts electricity through delocalised pi electrons between its layers. Thus the claim that diamond is a better electrical conductor than graphite is false, making it the 'not true' statement.