When burnt, which fiber has a sweet and fruity odor?

The correct answer, which is wool, has a distinct characteristic when burned that is often described as having a sweet and fruity odor. This unique scent arises from the high protein content in wool, which is made of keratin, a type of fibrous protein. When wool is subjected to heat, it tends to produce a smell reminiscent of burning hair or feathers, which is indeed sweeter and more pleasant than the odors produced by synthetic fibers such as polyester or nylon.

Cotton, while also a natural fiber, has a much different burning odor that tends to be more like burning paper, reflecting its cellulose structure. Synthetic fibers such as polyester and nylon produce more plasticky, chemical-like odors when burned. Thus, understanding the characteristics of various fiber types, including their behavior when burned, can greatly assist carpet cleaning technicians in identifying materials and applying the correct cleaning methods.