Which one among the following statements is not correct about graphite?

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Q: 83 (NDA-II/2010)

Which one among the following statements is not correct about graphite?

question_subject: 

Science

question_exam: 

NDA-II

stats: 

0,15,16,7,6,3,15

keywords: 

{'graphite': [0, 0, 3, 9], 'carbon': [1, 0, 4, 5], 'coal': [0, 1, 2, 0], 'stable allotrope': [0, 0, 1, 0], 'material': [0, 0, 0, 1], 'crystalline': [0, 0, 2, 1]}

Option 1 states that graphite is the most stable allotrope of carbon. This statement is correct. Allotrope refers to different forms of the same element with different physical and chemical properties. Graphite is indeed the most stable form of carbon and exists in a layered structure where each carbon atom is bonded to three other carbon atoms.

Option 2 claims that graphite is an electrically conducting material. This statement is also correct. Graphite has a unique structure that allows electrons to move freely along the layers, making it a good conductor of electricity.

Option 3 states that crystalline spherical beads of graphite have good lubricating properties under dry conditions. This statement is correct. The layered structure of graphite allows for easy sliding between the layers, reducing friction and making it an excellent lubricant. This property is particularly useful in dry conditions.

Option 4, however, states that graphite is the higher grade of coal. This statement is incorrect. Graphite and coal are entirely different substances. Coal is a sedimentary rock made up of fossilized plant matter, while graphite is a pure form of carbon. Alert - correct answer should be "Graphite is not a higher grade of coal."