Aldehydes, Ketones and Carboxylic Acids Mock Test – Class 12 Chemistry

1. The structure of -bromobutyraldehyde is:

2. Benzene reacts with ethanoic anhydride in the presence of anhydrous . The principal organic product is:

3. Match the feature in Column I with its description in Column II.

4. A cyclobutane ring bears both a methyl group and a group on the same ring carbon. Its name is:

5. Assertion: Mixing a carboxylic acid with ammonia at ordinary temperature does not necessarily produce an amide immediately.
Reason: The initial reaction is mainly proton transfer, giving an ammonium carboxylate salt that requires heating for dehydration.

6. Oxidation of produces:

7. Which statement about benzaldehyde is most appropriate?

8. Which sequence converts propanoic acid into propanal through a primary-alcohol intermediate?

9. Ethanal reacts with hydrogen cyanide, and the resulting cyanohydrin is hydrolysed completely. Which product is formed?

10. Assertion: Sodium borohydride generally does not convert a carboxylic acid into a primary alcohol under ordinary laboratory conditions.
Reason: A carboxylic acid can consume hydride through an acid-base reaction, and its acyl carbon is insufficiently reactive toward the mild reducing action of .

11. Compared with the bond in a typical alcohol, the bond in a carboxylic acid is more readily ionised mainly because:

12. A monocarboxylic acid has . Using the weak-acid approximation, which pair gives the equilibrium and percentage ionisation?

13. Consider the following statements about carboxylic-acid dimerisation.
Statement I: Dimerisation is especially important in vapour and non-polar media.
Statement II: A cyclic dimer contains two hydrogen bonds.
Statement III: Dimerisation helps explain the unusually high boiling points of carboxylic acids.
Statement IV: Dimerisation decreases the effective intermolecular attraction between acid molecules.

14. The carboxyl carbon of an open-chain carboxylic acid receives locant because:

15. The structural distinction between an aldehyde and a ketone is that:

16. Which row correctly classifies all the compounds shown?

17. A sample of ethanenitrile is completely converted into ethanal by Stephen reduction. What mass of ethanal is obtained, assuming complete conversion?

18. A sample of ethanol is subjected to controlled oxidation. In Step I, of the ethanol is converted into ethanal. In Step II, of that ethanal is oxidised to ethanoic acid. The acid is isolated in yield. Which pair gives the isolated acid mass and the mass of ethanal remaining after Step II?

19. Ketones generally undergo aldol addition more slowly than comparable aldehydes mainly because ketone carbonyl groups:

20. In a vessel, ethanal and , each initially , reach equilibrium with . The equilibrium mixture is then diluted to without adding reactants. How many moles of cyanohydrin decompose while the new equilibrium is established?

21. Benzene is to be converted into -phenylethanol through an aromatic ketone. Which reagent sequence is appropriate?

22. Butan--one, , is treated with of iodine and of hydroxide ions:

After the reaction, of hydrochloric acid is added to the carboxylate mixture. Which pair gives the iodoform mass formed and the moles of ethanoate remaining after acidification?

23. Assertion: Oxidation of a secondary alcohol normally preserves the number of carbon atoms in the product ketone.
Reason: Formation of the ketone involves conversion of the unit into without carbon-carbon bond cleavage.

24. The structure of benzal chloride is:

25. Match each common name in Column I with its IUPAC name in Column II.

26. Propanenitrile, , undergoes alkaline hydrolysis with conversion. Propanoic acid is obtained after acidification and isolated in yield. What pair gives the isolated acid mass and the volume of ammonia chemically formed at and ? Use , , and .

27. Which row gives the expected trend for alpha-haloethanoic acids?

28. A reaction record describes two concentration curves. Curve P rises while ethanal is kept with cold dilute alkali, but falls after the mixture is heated. Curve Q remains low initially and rises only after heating begins. What do P and Q most reasonably represent?

29. Replacing a hydrogen atom of methanoic acid with a methyl group generally lowers acidity because the methyl group:

30. An mixture of benzoic acid and phenol is treated with excess sodium bicarbonate. The carbon dioxide collected at STP has a volume of . Assume phenol does not react with bicarbonate. Which pair gives the mass percentage of benzoic acid and the amount of phenol in the mixture?

31. Assertion: Equal moles of benzoic acid and -nitrobenzoic acid produce equal volumes of hydrogen when each reacts completely with excess sodium under identical conditions.
Reason: Both substances are monocarboxylic acids and supply one replaceable carboxyl proton per molecule.

32. An ethanal molecule labelled with at its carbonyl carbon acts only as the electrophilic acceptor in an aldol reaction. An unlabelled ethanal molecule forms the enolate donor. In the product , the labelled carbon becomes:

33. A container labelled “concentrated ethanoic acid” should be handled differently from ordinary vinegar mainly because:

34. Consider the following statements about the Cannizzaro reaction.
Statement I: The aldehyde substrate must ordinarily lack an alpha hydrogen.
Statement II: One aldehyde molecule is oxidised while another is reduced.
Statement III: Concentrated alkali is used.
Statement IV: Ordinary ketones undergo the same reaction because they contain a carbonyl group.

35. Match each structural feature in Column I with its description in Column II.

36. Which row correctly classifies the product formed from the stated carboxylic acid?

37. A aldehyde sample is tested separately with excess Tollens reagent and excess Fehling solution. Silver is recovered with efficiency, while is recovered with efficiency. Each mole of aldehyde gives two moles of silver or one mole of . Which pair gives the recovered masses?

38. The proton-transfer equilibrium is:

Given and , which conclusion is correct?

39. Consider the sequence:

What is R?

40. During Clemmensen reduction, the oxidation number of the carbonyl carbon decreases by the same amount for an aldehyde and a ketone. What is this decrease?

41. Propanone labelled with specifically at one of its methyl carbons undergoes the iodoform reaction. If the labelled methyl group is the one converted into the haloform fragment, where is the label found?

42. A mixture of ethanol and propan--ol has a mass of . Both alcohols are completely oxidised to their corresponding acids. Ethanoic acid is isolated in yield, while propanoic acid is isolated in yield. Which pair gives the combined isolated acid mass and the mass of oxygen represented by consumed? Use:

43. In the structure , the aldehydic hydrogen is the hydrogen:

44. Which row gives a correct acyl-derivative conversion?

45. -Bromopropane, , is converted into butanenitrile in yield. Hydrolysis gives butanoic acid in yield, conversion to butanoyl chloride occurs in yield, and reaction with ammonia gives butanamide in yield. Which pair gives the final amide mass and the overall percentage yield? Use .

46. A mixture contains ethanal, propanone, and benzaldehyde. Complete reaction with -DNPH consumes of reagent. A separate identical mixture produces of silver with excess Tollens reagent. Another identical mixture gives of iodoform. Assume that each carbonyl compound consumes one mole of -DNPH, each aldehyde gives two moles of silver, and ethanal and propanone each give one mole of , while benzaldehyde gives none. Use and . What are the mole percentages of ethanal, propanone, and benzaldehyde, respectively?

47. A vinegar sample has density and contains ethanoic acid by mass. What volume of sodium hydroxide is required to neutralise the ethanoic acid in of the vinegar?

48. The alcohol that gives a positive iodoform test because oxidation produces a methyl ketone is:

49. The row describing the reaction with aqueous sodium bicarbonate is:

50. Methanal is treated with concentrated sodium hydroxide. The carboxylate product is separated, acidified, and then tested with Tollens reagent. Which observation sequence is expected?