Question

The armchair structure of a carbon nanotube is obtained when the nanotube axis is

• A. Parallel to the C–C bond
• B. Perpendicular to the C–C bond
• C. In any random direction with respect to C–C bond
• D. None of the above

Hint:

Armchair nanotubes (\( n = m \)) exhibit metallic behavior, whereas zigzag and chiral CNTs can be semiconducting.

Answer 1

The Correct Option is B

Carbon nanotubes (CNTs) can have different structures depending on the way graphene sheets are rolled. The three primary structures are: - Armchair (Metallic) – The nanotube axis is perpendicular to the C–C bond. - Zigzag (Semiconducting) – The nanotube axis is parallel to the C–C bond. - Chiral (Semiconducting) – The nanotube axis is at an angle to the C–C bond. Step 1: Understanding the Armchair Structure - In the armchair configuration, graphene is rolled in such a way that the hexagonal carbon rings form a continuous chain along the tube’s circumference. - This structure makes armchair CNTs metallic in nature.


Step 2: Identifying the Correct Answer Since armchair nanotubes form when the nanotube axis is perpendicular to the C–C bond, the correct answer is option (B).