Q. Which element is used in the manufacture of safety matches?
Answer: Phosphorous
Notes:

One end of a match is coated with a material that can be ignited by frictional heat generated by striking the match against a suitable surface. The coated end of a match, known as the match "head," contains either phosphorus or phosphorus sesquisulfide as the active ingredient and gelatin as a binder. The tip of the strike-anywhere match contains phosphorus sesquisulfide, P4S3, a nontoxic, stable compound, which is converted to flammable white phosphorus when the match-head is dragged across a rough surface.  (The match-head usually also contains powdered glass to increase the friction.)  Once the white phosphorus ignites, it causes potassium chlorate, KClO3, in the match-head to burn, producing molecular oxygen, which further feeds the combustion reaction, until the wooden stick starts to burn.  In safety matches, the phosphorus is not in the match-head, but is instead on the side of the box, thus separating the components that are necessary to ignite the match.  Dragging the match-head across the rough surface of the box converts some of the red phosphorus into white phosphorus, which ignites the match-head, once again causing potassium chlorate to produce molecular oxygen.