NEET UG · Chemistry

Aldehydes, Ketones and Carboxylic Acids

18 practice questions, each with the answer and an explanation.

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Random questions from this topic, one at a time. You see the answer and the explanation straight after each one.

All 18 questions

  1. Which reaction selectively converts an acyl chloride (acid chloride) into an aldehyde using hydrogen gas over a palladium catalyst poisoned with barium sulfate and quinoline?
  2. What is the correct decreasing order of reactivity of the following carbonyl compounds toward nucleophilic addition reactions: Formaldehyde (I), Acetaldehyde (II), Acetone (III), and Di-tert-butyl ket…
  3. In the reaction of an aldehyde or ketone with semicarbazide (H2N-NH-CO-NH2), why does condensation occur exclusively at the hydrazine amino group (-NH-NH2) rather than the amide amino group (-CO-NH2)?
  4. Which synthetic reduction method is most appropriate for converting an acid-sensitive carbonyl compound containing an acetal functional group into an alkane?
  5. Why does benzaldehyde give a positive Tollen's test (depositing a silver mirror) but fails to reduce Fehling's solution to form a red cuprous oxide precipitate?
  6. Which of the following organic compounds will yield a bright yellow crystalline precipitate of iodoform (CHI3) when warmed with iodine and aqueous sodium hydroxide (the haloform test)?
  7. What is the major product obtained when acetaldehyde (CH3CHO) is treated with dilute sodium hydroxide solution and subsequently heated?
  8. What products are formed when benzaldehyde (C6H5CHO), an aldehyde lacking α-hydrogens, is treated with concentrated (50%) aqueous sodium hydroxide (the Cannizzaro reaction)?
  9. In a crossed Cannizzaro reaction between benzaldehyde (C6H5CHO) and formaldehyde (HCHO) in the presence of concentrated sodium hydroxide, which species is oxidized to sodium formate, and why?
  10. Why are carboxylic acids significantly stronger acids than phenols, despite both compounds possessing acidic hydroxyl (-OH) groups attached to unsaturated carbon atoms?
  11. Which sequence correctly arranges the substituted acetic acid derivatives in decreasing order of their acid strength (Ka)?
  12. Why is ortho-substituted benzoic acid (such as o-nitrobenzoic acid or o-toluic acid) a stronger acid than benzoic acid and its corresponding meta- and para-isomers (the ortho-effect)?
  13. Why is thionyl chloride (SOCl2) the preferred chemical reagent over phosphorus pentachloride (PCl5) or phosphorus trichloride (PCl3) for converting carboxylic acids into acyl chlorides?
  14. What is the product formed when propanoic acid (CH3CH2COOH) is treated with bromine (Br2) in the presence of a catalytic amount of red phosphorus, followed by hydrolysis (the Hell-Volhard-Zelinsky rea…
  15. What is the alkane obtained when anhydrous sodium ethanoate (CH3COONa) is heated with soda-lime (NaOH + CaO)?
  16. Why does benzaldehyde not undergo Friedel-Crafts alkylation or acylation reactions in the presence of anhydrous aluminum chloride (AlCl3)?
  17. Which product is obtained when phthalic acid (benzene-1,2-dicarboxylic acid) is strongly heated with ammonia (NH3)?
  18. What is the structural reagent used in the Etard reaction to oxidize toluene selectively to benzaldehyde?

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