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JAMB Chemistry 1994 Question 46

Question 46

Hydrocarbons

One mole of a hydrocarbon contains 48 g of carbon. If its vapour density is 28, the hydrocarbon is [C = 12, H = 1]

  1. A.an alkane
  2. B.an alkene
  3. C.an alkyne
  4. D.aromatic
Show the answer and explanation

Answer: B (an alkene)

Explanation

M = 2 × 28 = 56. 48 g of carbon is 4 C atoms, leaving 8 g = 8 H atoms, so the formula is C4H8. This fits CnH2n, an alkene.