Which of the following is not a crystalline allotropic form of carbon?

1. Graphite

2. Diamond

3. Fullerene

4. Coal

Carbon shows allotropy. ___ and ___ are the two most important crystalline allotropic forms.

Which of the following is not a crystalline form of carbon?

Ishita wanted to select one of the allotropic forms of carbon as a lubricant for fast moving machinery parts. Which material should she use and why?

(Hint: Recall the structure and uses of crystalline forms of carbon.)