Cyclopropane is an interesting hydrocarbon. Instead of having three carbons in a row, the three carbons form a ring, as shown in this perspective drawing (see Figure 2.18 for a prior example of this kind of drawing):

Cyclopropane was at one time used as an anesthetic, but its use was discontinued, in part because it is highly flammable. (b) The three carbon atoms are necessarily in a plane. What do the different wedges mean?