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List four observations that indicate that a chemical reaction may be taking place

The twister and runaway train are two coasters at the same amusement park. both coasters start at the same height. the coaster for the twister is twice the mass of the coaster for the runaway train. which roller coaster has greater gravitational potential energy at the start of the ride?

Acetylene gas c2h2 undergoes combustion to produce carbon dioxide and water vapor how many grams of water are produced by the same amount of c2h2?