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JAMB Chemistry 2004 Question 40

Question 40

Hydrocarbons

Oxyacetylene flame is used for iron-welding because it

  1. A.makes the iron metal solidify very quickly
  2. B.combines with oxygen to give a pop sound
  3. C.evolves a lot of heat when burnt
  4. D.dissociates to produce carbon (IV) oxide and oxygen
Show the answer and explanation

Answer: C (evolves a lot of heat when burnt)

Explanation

Ethyne burning in oxygen gives a very hot flame (about 3000°C), hot enough to melt iron.