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JAMB Chemistry 1992 Question 49

Question 49

Alkanals and Alkanones

Alkanals can be differentiated from alkanones by reaction with

  1. A.2,4-dinitrophenylhydrazine
  2. B.hydrogen cyanide
  3. C.sodium hydrogen sulphite
  4. D.Tollen's reagent.
Show the answer and explanation

Answer: D (Tollen's reagent.)

Explanation

Alkanals are easily oxidised and give a silver mirror with Tollen's reagent; alkanones do not. Both react with 2,4-DNPH, HCN and NaHSO3.