Which one of the following is not true for the form of car bon known as diamond?

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Q: 26 (CDS-II/2018)

Which one of the following is not true for the form of car bon known as diamond?

question_subject: 

Science

question_exam: 

CDS-II

stats: 

0,26,20,4,9,26,7

keywords: 

{'different carbon': [0, 0, 0, 1], 'carbon': [1, 0, 4, 5], 'graphite': [0, 0, 3, 9], 'carbon distance': [0, 0, 0, 1], 'car bon': [0, 0, 0, 1], 'better electric conductor': [0, 0, 0, 1], 'diamond': [0, 0, 3, 3]}

Option 1: It is harder than graphite.

This option is true. Diamond is indeed harder than graphite. This is because the carbon atoms in diamond are arranged in a three-dimensional lattice structure, which gives it its hardness. On the other hand, graphite has a layered structure, making it relatively softer.

Option 2: It contains the same percentage of carbon as graphite.

This option is true. Both diamond and graphite are forms of carbon, and therefore, they both consist of pure carbon. So, they do contain the same percentage of carbon.

Option 3: It is a better electric conductor than graphite.

This option is not true. Diamond is actually a poor conductor of electricity. This is because each carbon atom in diamond is covalently bonded to four other carbon atoms, creating a completely filled valence band that does not allow the movement of electrons necessary for electrical conductivity.

Option 4: It has different carbon to carbon distance in all directions.

This option is true. Diamond has a tetrahedral crystal structure, where each carbon atom is bonded to four neighboring carbon atoms. As a result, diamond has a uniform carbon to carbon distance in all directions.