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JAMB Chemistry 1997 Question 48

Question 48

Alkanals and Alkanones

When Fehling's solution is added to two isomeric carbonyl compounds X and Y with the molecular formula C5H10O, compound X gives a red precipitate while Y does not react. It can be inferred that X is

Diagram for this question
  1. A.CH3COCH2CH2CH3
  2. B.CH3CH2CH2CH2CHO
  3. C.CH3CH2COCH2CH3
  4. D.CH3CH(CH3)COCH3
Show the answer and explanation

Answer: B (CH3CH2CH2CH2CHO)

Explanation

Fehling's solution gives a red precipitate (Cu2O) with aldehydes but not with ketones. Only B has the –CHO group (pentanal); the others are ketones.