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Q110 (NDA-II/2025) Science & Technology › Basic Science (Physics, Chemistry, Biology) › Basic chemical principles Answer Verified

Which one of the following statements is NOT correct ?

Result
Your answer: —  Â·  Correct: C
Explanation

Diamond is an allotrope of carbon characterized by a giant covalent structure where each carbon atom is tetrahedrally bonded to four others. This extended covalent network makes diamond the hardest known natural substance [2]. Unlike graphite, which has delocalized electrons that allow for electrical conductivity, diamond's valence electrons are tightly held within these covalent bonds and are not free to move. Consequently, diamond is a poor electrical conductor (an insulator), making statement 3 incorrect. Fullerene (C60) consists of carbon atoms arranged in five and six-membered rings resembling a football [1]. Graphite's layered structure, held together by weak intermolecular forces, allows layers to slide over each other, making it an effective lubricant.

Sources

  1. [1] Science , class X (NCERT 2025 ed.) > Chapter 4: Carbon and its Compounds > Allotropes of carbon > p. 61
  2. [2] Science , class X (NCERT 2025 ed.) > Chapter 3: Metals and Non-metals > Table 3.1 > p. 40
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SIMILAR QUESTIONS

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NDA-II · 2012 · Q76 Relevance score: 3.30

Consider the following statements: 1. Diamond is hard and graphite is soft. 2. Diamond is soft and graphite is hard. 3. Diamond is a bad conductor, but graphite is a good conductor. 4. Diamond is a good conductor, but graphite is a bad conductor. Which of the statement(s) given above is/are correct?