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NDA 2 2025 GAT, question 110

Topic: Chemistry

Q110

Which one of the following statements is NOT correct ?

  1. (a) Diamond is hard due to extended covalent bonding in it
  2. (b) Fullerene is composed of five and six membered rings
  3. (c) Diamond is a good conductor of electricityCorrect answer
  4. (d) Graphite is used as a lubricant

Solution.

Answer: (c) Diamond is a good conductor of electricity

  1. Diamond’s carbon atoms use their valence electrons in a rigid covalent network, leaving no mobile electrons for ordinary electrical conduction.
  2. Graphite has mobile electrons and sliding layers; fullerenes such as C₆₀ contain five- and six-membered rings.
  3. Therefore (c) is false.