Carbon allotropy (materials science): Which is the hardest allotropic form of carbon known for extreme hardness and abrasion resistance? Identify the correct carbon allotrope noted for its tetrahedral network and highest Mohs hardness. Choose the correct option.

Difficulty: Easy

Coke
Graphite
Diamond
Charcoal

Correct Answer: Diamond

Explanation:

Given data

Asked: the hardest allotropic form of carbon.

Concept/Approach
Carbon occurs in several allotropes (diamond, graphite, amorphous carbon such as charcoal/coke). Diamond has a 3D network of sp³-hybridized carbon atoms, giving it the highest hardness.

Why others are wrong
• Graphite is soft and lubricating (layered sp² sheets).• Charcoal and coke are amorphous and much softer.

Final Answer
Diamond

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