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Q93 (NDA-II/2009) Science & Technology › Basic Science (Physics, Chemistry, Biology) › Basic chemical principles Answer Verified

Diamond is a

Result
Your answer: —  Â·  Correct: C
Explanation

Diamond is an allotrope of carbon characterized by its extreme physical properties. It is recognized as the hardest naturally occurring substance known, scoring a 10 on the Mohs scale of mineral hardness [1]. This hardness arises from its rigid three-dimensional tetrahedral structure where each carbon atom is covalently bonded to four others [4]. Regarding electrical properties, diamond is a non-conductor (electrical insulator) because all its valence electrons are tightly held in these covalent bonds, leaving no free electrons to carry an electric current [3]. While it is an exceptional thermal conductor, its high electrical resistivity (ranging from 10^12 to 10^13 ohm-m) classifies it as an insulator [2]. In contrast, graphite, another carbon allotrope, is soft and a good conductor due to its layered structure and free electrons [4].

Sources

  1. [1] Science , class X (NCERT 2025 ed.) > Chapter 4: Carbon and its Compounds > Allotropes of carbon > p. 61
  2. [4] Science , class X (NCERT 2025 ed.) > Chapter 3: Metals and Non-metals > Table 3.1 > p. 40
  3. [2] Science , class X (NCERT 2025 ed.) > Chapter 11: Electricity > Activity 11.3 > p. 179
  4. [3] Science-Class VII . NCERT(Revised ed 2025) > Chapter 4: The World of Metals and Non-metals > 4.1.5 Conduction of electricity > p. 48
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SIMILAR QUESTIONS

NDA-II · 2012 · Q76 Relevance score: 6.46

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?

NDA-II · 2025 · Q110 Relevance score: 3.93

Which one of the following statements is NOT correct ?

NDA-II · 2008 · Q43 Relevance score: 3.51

Assertion (A) : Diamond is a good conductor of electricity. Reason(R): Diamond and graphite are two allotrope of carbon and graphite is a good conductor of electricity.

CDS-II · 2014 · Q26 Relevance score: 2.12

The form of carbon known as graphite

NDA-I · 2011 · Q36 Relevance score: 1.47

Which of the following statements about diamond are correct ? 1. It is used as a gem in jewellery because of its ability to reflect light 2. It is a good conductor of electricity 3. It is used for cutting glass, marble stones and other hard materials 4. It is used for drilling of rocks Select the correct answer using the code given below :