Fullerenes are _________ (crystalline/amorphous) forms of carbon.

Explanation

**Step-by-Step Solution:**

1. **Understanding Fullerenes**: Fullerenes are a specific form of carbon molecules that can take on various shapes, the most famous being Buckminsterfullerene, which is composed of 60 carbon atoms arranged in a structure resembling a soccer ball.

2. **Identifying the Nature of Fullerenes**: To determine whether fullerenes are crystalline or amorphous, we need to understand the characteristics of both forms. Crystalline forms have a definite and regular shape, and they exhibit a smooth surface when cut. They also have sharp melting and boiling points.

3. **Analyzing the Structure of Fullerenes**: The structure of Buckminsterfullerene (C60) consists of hexagonal and pentagonal rings, which indicates that it has a well-defined geometric arrangement. This regular arrangement is a key characteristic of crystalline solids.

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