Which of the following is NOT an allotrope of Carbon?

Correct option is B

The correct answer is (B) Carbon dioxide.

Allotropes of Carbon refer to different forms of the same element, carbon, where the atoms are bonded in different structures.

• A) Diamond: An allotrope of carbon where carbon atoms are arranged in a three-dimensional crystalline structure. It is the hardest known natural material.
• C) Graphite: Another allotrope of carbon, where carbon atoms are arranged in layers of hexagonal patterns. It is a good conductor of electricity and is used in pencils.
• D) Fullerenes: These are allotropes of carbon, consisting of molecules made entirely of carbon, such as the buckyball (C₆₀), which resembles a soccer ball.

 Carbon dioxide is not an allotrope of carbon. It is a chemical compound consisting of carbon and oxygen (CO₂), not just carbon atoms bonded in different forms.