Definition: Given a scientific passage and an answer, generate a question for the given answer.
Input: Passage: Note Acetylene is used in oxyacetylene torches for cutting and welding metals. The flame from such a torch can be very hot. Most acetylene, however, is converted to chemical intermediates that are used to make vinyl and acrylic plastics, fibers, resins, and a variety of other products. Answer: acetylene
Output:
Which material used in oxyacetylene torches helps cut and weld metals?