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

1. Ethanal and propanal are mixed under conditions where both self-aldol and crossed-aldol additions are possible. Ignoring stereoisomers, what is the minimum number of constitutionally different beta-hydroxy aldehydes expected from the two self-additions and the two possible donor-acceptor crossed additions?

2. How many alpha hydrogens are present in one molecule of butan--one, ?

3. In a vessel, of ethanoic acid and of ethanol are allowed to reach equilibrium:

At equilibrium, of ester is present. What is ?

4. The tertiary alcohol -methylhexan--ol has methyl, ethyl, and propyl groups attached to its hydroxyl-bearing carbon. How many distinct ketone-Grignard reagent pairs can produce this alcohol in a single Grignard addition followed by hydrolysis?

5. Benzaldehyde labelled with deuterium at its aldehydic position, , acts as the hydride-donor molecule in a Cannizzaro reaction. Where is the deuterium expected after the hydride-transfer step and protonation?

6. A (0.300,mathrm{mol}) mixture of methanal and ethanal has a mass of (11.8,mathrm{g}). One sample is treated with excess Tollens reagent under conditions in which methanal is completely oxidised to carbonate. An identical sample is subjected to the iodoform test. Assume that one mole of methanal deposits four moles of silver, while one mole of ethanal deposits two moles of silver. Which pair gives the theoretical silver mass and iodoform mass? Use (M(mathrm{Ag})=108,mathrm{g,mol^{-1}}) and (M(mathrm{CHI_3})=394,mathrm{g,mol^{-1}}).

7. Benzaldehyde, , is treated with of phenylhydrazine having density and purity :

If the phenylhydrazone is isolated in yield, what mass is obtained? Use and .

8. Assertion: Benzoic acid does not undergo the ordinary Hell-Volhard-Zelinsky reaction.
Reason: Benzoic acid has no alpha carbon bearing an alpha hydrogen next to its carboxyl group.

9. An acid anhydride contains:

10. A sample of a saturated acyclic ketone gives of ethanoic acid and of propanoic acid on quantitative vigorous oxidation:

Which pair gives the molecular formula of the ketone and the mass of oxygen represented by that is consumed?

11. Toluene containing specifically at its methyl carbon is converted into benzaldehyde through benzal chloride. The isotope will be located at:

12. Propanal, , is treated with of methylmagnesium bromide. After hydrolysis, butan--ol is isolated in yield. If nucleophilic attack occurs equally from both faces of the planar propanal carbonyl group, what mass of each enantiomer is obtained?

13. For compounds of broadly comparable molar mass, the most reasonable increasing order of boiling point is:

14. A model shows the carbonyl carbon bonded to oxygen and two other atoms. The three sigma bonds lie in one plane, while electron density occurs above and below that plane. The electron density above and below the plane represents:

15. A compound X has molecular formula . It gives a -DNPH precipitate and a positive iodoform test but does not reduce Tollens reagent. X is treated with , and the cyanohydrin is hydrolysed completely. The evidence supports the conclusion that:

16. Propanal vapour occupies at and . In a Tollens test, of the propanal reacts. Metallic silver is recovered with efficiency, and propanoic acid after acidification is recovered in yield. Which pair gives the recovered silver mass and recovered acid mass? Use .

17. A mixture of sodium ethanoate and sodium propanoate has a mass of . Complete soda-lime decarboxylation gives methane and ethane. Which pair gives the methane volume percentage in the gaseous hydrocarbon mixture and the total gas volume at STP?

18. The bond most directly responsible for proton donation by a carboxylic acid is:

19. A mixture of methanal and propanone reacts completely with excess methylmagnesium bromide, followed by hydrolysis. The resulting alcohol mixture is treated with acidified dichromate. Ethanol is oxidised according to

while tert-butanol does not react under the stated conditions. If of is consumed, what was the mole percentage of methanal in the original carbonyl mixture?

20. Evaluate the following statements.
Statement I: Rosenmund reduction uses a moderated palladium catalyst to stop an acyl chloride at the aldehyde stage.
Statement II: Stephen reduction forms an imine salt that gives an aldehyde on hydrolysis.
Statement III: The Hell-Volhard-Zelinsky reaction requires at least one alpha hydrogen.
Statement IV: Kolbe electrolysis of one saturated monocarboxylate salt generally gives a symmetrical alkane containing an odd number of carbon atoms.

21. Which row correctly describes amide formation?

22. Four unknown compounds give the results shown.

Which assignment is correct?

23. A cyclopentane ring bears a group at ring carbon and a methyl group at the adjacent ring carbon. The compound is named:

24. A mixture of ethanal and propanone is completely reduced by the Clemmensen method. The resulting mixture of ethane and propane has a mass of . Which pair gives the total gas volume at STP and the volume percentage of ethane? Use at STP.

25. What is the principal cathodic reaction during electrolysis of an aqueous sodium carboxylate solution under ordinary Kolbe conditions?

26. Match each property in Column I with its most suitable explanation in Column II.

27. Assertion: Ethanoic acid and methyl methanoate are functional isomers.
Reason: Both compounds have the molecular formula , but one contains and the other contains .

28. A mixture initially contains of a carbonyl compound, of methanol, and of water. At equilibrium, of dimethyl acetal has formed according to

Which pair gives and the percentage conversion of the carbonyl compound?

29. Ethanal and ethanoic acid are present in an analytical sample with a total mass of . One sample gives of carbon dioxide at STP with excess sodium bicarbonate. An identical sample is treated with excess Tollens reagent. Which pair gives the mass percentage of ethanoic acid and the theoretical mass of silver deposited? Use .

30. Why is thionyl chloride often preferred over phosphorus pentachloride for preparing a pure acyl chloride from a carboxylic acid?

31. The oxygen atom of a carbonyl group can act as a basic or nucleophilic site mainly because it:

32. Assertion: Benzaldehyde is usually negative toward Fehling solution in standard textbook treatment.
Reason: Aromatic aldehydes generally do not reduce the alkaline copper(II)-tartrate complex readily under the test conditions.

33. Butanoic acid, , is treated with of bromine under Hell-Volhard-Zelinsky conditions:

The alpha-bromo acid is isolated in yield. Which pair gives the isolated product mass and the mass of unreacted butanoic acid? Use and .

34. The structure corresponding to -methylbut--enoic acid is:

35. The appropriate IUPAC name for is:

36. Assertion: The carboxyl group is meta directing in electrophilic aromatic substitution.
Reason: Sigma complexes formed during ortho and para attack are especially destabilised by resonance interaction with the electron-withdrawing carboxyl group.

37. An alkene gives ethanal and propanone on reductive ozonolysis. The alkene is:

38. Methanoic acid undergoes the sequence

What is S?

39. Consider the following statements.
Statement I: Resonance contributors are not separate species rapidly changing into one another.
Statement II: The actual carboxylate ion is a resonance hybrid.
Statement III: Delocalisation lowers the energy of the carboxylate ion.
Statement IV: Resonance destabilisation makes carboxylic acids stronger than alcohols.

40. The ionic equation for Fehling oxidation is:

What masses of anhydrous and supply the stoichiometric amounts of and needed to oxidise of aldehyde? Use and .

41. Which row correctly classifies all the compounds shown?

42. Four acids have the values shown below.

Which order of decreasing acid strength is correct?

43. Ketones generally resist further oxidation by mild oxidising agents because:

44. 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?

45. The reaction sample contains of ethanal and of propanone. It is treated with of a sodium borohydride sample that is pure. Assume one mole of supplies four usable hydride equivalents and ethanal is reduced before propanone. Which pair gives the total alcohol mass formed and the mass of unreacted propanone? Use .

46. Consider the following statements about ketone nomenclature.
Statement I: The parent chain must contain the carbonyl carbon.
Statement II: The carbonyl group receives the lowest possible locant before ordinary alkyl substituents are considered.
Statement III: A ketone group is expressed by the prefix when a higher-priority functional group supplies the suffix.

47. A student argues that aldehydes and ketones should boil as high as alcohols because all three classes contain oxygen. The most suitable correction is:

48. The molecular formula alone does not prove that a compound is an aldehyde or ketone because it can also represent:

49. A mixture of methanal and benzaldehyde undergoes a selective crossed Cannizzaro reaction in which all benzaldehyde reacts and methanal is present in excess. Benzyl alcohol is isolated in yield, giving . Which pair gives the initial benzaldehyde mole percentage and the mass of methanal left unreacted?

50. The table proposes effects of aromatic substituents on benzoic-acid strength.

Which row is correct?