Question 17
Which are the crystalline forms of carbon?
The right answer is the one marked above.
Diamond, graphite and fullerene. In the crystalline forms the atoms are arranged in a definite pattern, and it is these forms that show allotropy.
Charcoal, lamp black and coal are the amorphous forms — no definite pattern. The two behave differently in chemistry too: carbon is of low reactivity, but the amorphous forms such as charcoal do react, burning in oxygen to form carbon dioxide.