Aldehydes Ketones and Carboxylic Acids — CBSE Class 12 board PYQs

Which one of the following has the lowest pKₐ value?

Assertion (A): Bromination of benzoic acid gives m-bromobenzoic acid.
Reason (R): The carboxyl group increases the electron density at the meta position.

What is the correct IUPAC name of the compound shown in the figure (CH₃CH₂C(CH₃)₂COOH)?

Write the IUPAC name of the compound shown in the figure (3,5-dimethylphenyl ethanoate).

Write the IUPAC name of the compound shown in the figure (3-bromo-5-chlorobenzoic acid).

Draw the structure of 4-chloropentan-2-one.

Draw the structure of 3-methylbutanal.

Draw the structural formula of the 1-phenylpropan-1-one molecule.

Write the structural formula of 1-phenylpentan-1-one.

Write the structure of 3-oxopentanal.

Write the IUPAC name of the compound (CH₃)₃CCH₂COOH.

What IUPAC name would you give to the compound shown in the figure (CH₃CO–CH₂–CH(Cl)–CH₃)?

Draw the structure of the compound whose IUPAC name is 4-chloropentan-2-one.

Arrange the following compounds in increasing order of their acid strengths:
(CH₃)₂CHCOOH, CH₃CH₂CH(Br)COOH, CH₃CH(Br)CH₂COOH.

Write the chemical equation for the conversion of benzonitrile to acetophenone.

Name the following compound according to the IUPAC system: CH₃COCH₂COCH₃.

Write the IUPAC name of the compound shown in the figure ((CH₃)₂CH–CO–CH(CH₃)₂).

Complete the following reaction:

Draw the structural formula of hex-2-en-4-ynoic acid.

Write the IUPAC name of CH₃CH(CH₃)CH₂C(CH₃)₂COCH₃.

Write the IUPAC name of CH₃COCH₂COCH₃.

How is acetone obtained from ethanol?

Write the IUPAC name of the compound shown in the figure (2-methylcyclohexan-1-one).

Write the IUPAC name of the compound shown in the figure (ethyl 4-chlorobenzoate).

Give the IUPAC name of the compound shown in the figure ((CH₃)₂CH–CO–CH₂–CH(CH₃)₂ skeleton as printed).

Mention a chemical property in which methanoic acid differs from acetic acid.

How are formalin and trioxane related to methanal?

Write the IUPAC name of the compound shown in the figure (cyclohexyl–CH₂–CHO).

Write the IUPAC name of the compound shown in the figure (CH₃COO–C₆H₄–CH₃, para).

Draw the structure of 4-methylpent-3-en-2-one.

Write the IUPAC name of (CH₃)₂C=CH–CO–CH₃.

Write the IUPAC name of the compound shown in the figure (C₆H₅CH₂CHO).

Write the IUPAC name of the compound shown in the figure (CH₃CH₂CH(Br)COOH).

Write chemical tests to distinguish between formic acid and acetic acid.

Mention one important use of methanoic acid.

What product is obtained when ethylbenzene is oxidised with alkaline KMnO₄?

Write the chemical reaction for getting 2-propanol from ethanal.

Give one chemical test to distinguish between acetaldehyde and benzaldehyde.

Name two important uses of formalin.

Draw the structure of the major product of the reaction shown in the figure (part a).

Arrange the following in increasing order of the property indicated:
a) ethanal, propanone, propanal, butanone (reactivity towards nucleophilic addition)
b) 4-nitrobenzoic acid, benzoic acid, 3,4-dinitrobenzoic acid, 4-methoxybenzoic acid (acid strength)

Explain the following reactions:
a) Clemmensen reduction
b) Stephen reaction

a) Complete the following:
i) CH₃CN →1. DIBAL-H 2. H₂O→ 'A' →NH₂OH/H⁺→ 'B'
ii) Write the IUPAC name of the compound shown in the figure (3-bromobenzaldehyde).
iii) Write a chemical test to distinguish between phenol and benzoic acid.

b) Convert the following:
i) benzoic acid to benzaldehyde
ii) propan-1-ol to 2-bromopropanoic acid
iii) acetaldehyde to but-2-enal

What happens when:
(a) propanone is treated with methyl magnesium iodide and then hydrolysed;
(b) benzene is treated with CH₃COCl in the presence of anhydrous AlCl₃?

Complete the following reactions:
(i) (the reaction shown in the figure)
(ii) (C₆H₅CH₂)₂Cd + 2CH₃COCl →
(iii) (the reaction shown in the figure)

Write chemical equations for the following reactions:
(i) propanone is treated with dilute Ba(OH)₂
(ii) acetophenone is treated with Zn(Hg)/conc. HCl
(iii) benzoyl chloride is hydrogenated in the presence of Pd/BaSO₄

How do you convert the following?
(a) ethanal to propanone
(b) toluene to benzoic acid

Account for the following:
(a) Aromatic carboxylic acids do not undergo Friedel–Crafts reactions.
(b) The pKₐ value of 4-nitrobenzoic acid is lower than that of benzoic acid.

(A), (B) and (C) are three non-cyclic functional isomers of a carbonyl compound with molecular formula C₄H₈O. Isomers (A) and (C) give a positive Tollens' test whereas (B) does not, but (B) gives a positive iodoform test. (A) and (B) on reduction with Zn(Hg)/conc. HCl give the sa …

Write the structures of the main products of the three reactions shown in the figure.

Name the reagents used in the following reactions:
i) (the carbonyl reduction shown in the figure)
ii) C₆H₅–CH₂–CH₃ → C₆H₅–COO⁻K⁺

Predict the products of the following reactions:
i) (the reaction shown in the figure)
ii) C₆H₅–CO–CH₃ →NaOH/I₂→ ? + ?
iii) CH₃COONa →NaOH/CaO, Δ→ ?

State:
i) why benzaldehyde does not undergo aldol condensation;
ii) how an acid amide may be converted to the parent acid.

Describe the following reactions:
i) Cannizzaro's reaction
ii) cross aldol reaction

State reasons for the following situations:
i) Monochloroethanoic acid is a weaker acid than dichloroethanoic acid.
ii) Benzoic acid is a stronger acid than ethanoic acid.

Write chemical tests to distinguish between the following pairs of compounds:
i) acetophenone and benzophenone
ii) ethanal and propanal

State chemical tests to distinguish between the following pairs of compounds:
i) propanal and propanone
ii) phenol and benzoic acid

Give chemical tests to distinguish between:
i) acetaldehyde and benzaldehyde
ii) propanone and propanol

How can the following conversions be carried out?
a) ethanol to acetone
b) benzene to acetophenone
c) benzoic acid to benzaldehyde

An organic compound A contains 69.77% C, 11.63% H and the rest oxygen; its molecular mass is 86. It does not reduce Tollens' reagent but forms an addition product with sodium hydrogen sulphite and gives a positive iodoform test. On vigorous oxidation it gives ethanoic and propano …

Giving a chemical equation for each, illustrate the following processes:
a) Cannizzaro reaction
b) acetylation
c) decarboxylation

How would you account for the following?
i) Aldehydes are more reactive than ketones towards nucleophiles.
ii) The boiling points of aldehydes and ketones are lower than those of the corresponding acids.
iii) Aldehydes and ketones undergo a number of addition reactions.

Complete the reaction statements shown in the figure by giving the missing starting material, reagent or product (parts b and c as printed; part a is incomplete in the source).

Give chemical tests to distinguish between the following pairs of compounds:
i) propanal and propanone
ii) benzaldehyde and benzoic acid

Explain the mechanism of nucleophilic addition to a carbonyl group and give one example of such an addition reaction.

How would you bring about the following conversions?
i) propanal to butanone
ii) benzaldehyde to benzophenone
iii) benzoyl chloride to benzonitrile

a) Write the steps and conditions involved in the following conversions:
i) acetophenone to 2-phenyl-2-butanol
ii) propene to acetone
b) Describe a simple chemical test to distinguish between diethyl ether and propanol.

Write chemical equations to illustrate each of the following reactions:
i) acylation reaction
ii) Rosenmund reduction

Give reasons for the following:
a) Carboxylic acids do not give the characteristic reactions of the carbonyl group.
b) Treatment of benzaldehyde with HCN gives a mixture of two isomers which cannot be separated even by careful fractional distillation.
c) Sodium bisulphite is used …

Give chemical tests to distinguish between the following pairs of compounds:
i) phenol and benzoic acid
ii) benzaldehyde and acetophenone

Write the names of the reagents and equations for the conversion of:
i) phenol to salicylaldehyde
ii) anisole to p-methoxyacetophenone

How are the following conversions carried out?
i) ethanol to ethane-1,2-diol
ii) phenol to acetophenone

Draw the structure of a carbonyl group and indicate clearly:
i) the hybridised state of carbon
ii) the σ and π bonds present
iii) the electrophilic and nucleophilic centres in it

Write the IUPAC names of the two compounds shown in the figure (an unsaturated dicarboxylic skeleton and a polysubstituted benzoic acid).

Write the IUPAC names of the following:
i) (the aryl propanoate shown in the figure)
ii) CH₃–C≡C–CH₂–CHO

Write one chemical reaction each to exemplify:
i) Rosenmund reduction
ii) Tollens' reagent

Write chemical tests to distinguish between:
a) acetaldehyde and acetone
b) acetic acid and acetaldehyde
c) phenol and propanoic acid

State the sequence of steps to obtain:
a) acetophenone from benzene
b) acetone from acetyl chloride

Give one test each to distinguish between:
i) aqueous solutions of acetaldehyde and acetone
ii) aqueous solutions of phenol and benzoic acid
iii) aqueous solutions of formaldehyde and acetaldehyde

i) Most aromatic acids are solids while acetic acid and others of its series are liquids. Explain why.
ii) Explain why ketones are less reactive towards nucleophiles than aldehydes.

i) Give one example each of acetals and oximes.
ii) Why is benzoic acid stronger than acetic acid?

Write reactions for obtaining:
i) acetone from acetic acid
ii) benzene from toluene

Complete the following reaction equations:
i) RCHO →Zn(Hg), HCl→
ii) CH₃CONH₂ + HNO₂ →

Write the IUPAC names of the following compounds:
i) CH₃CH₂CH₂CH₂CH₂COOH
ii) (the nitro-aromatic amine shown in the figure)

Write reactions with conditions for the following conversions:
i) methyl bromide to acetic acid
ii) benzene to toluene

Describe the trans-esterification reaction, giving an example.

Write reactions and conditions for the following conversions:
a) ethanal to propanone
b) benzoyl chloride to benzaldehyde
c) acetaldehyde to crotonaldehyde

Write the IUPAC name of the compound shown in the figure (the acetate ester of 3,5-dimethylphenol, as printed in the A.I. 2000 paper).

Give the IUPAC names of the two compounds shown in the figure:
i) (CH₃)₂CHCH₂COCl
ii) CH₃CH₂CO–O–COCH₃

How can 2-butanol be obtained from ethanol? State the conditions for the reactions involved.

a) Give one example of the Wolff–Kishner reduction.
b) Write the IUPAC name of the compound shown in the figure (benzene-1,4-dicarbaldehyde).
c) Convert acetaldehyde to methane.

Account for the following:
i) Ethers possess a dipole moment even if the alkyl radicals in the molecule are identical.
ii) Sodium bisulphite is used for the purification of aldehydes and ketones.

Write the structures of compounds A, B and C in the following reactions:
a) CH₃COOH →NH₃, Δ→ A →Br₂/KOH(aq)→ B →CHCl₃ + alc. KOH→ C
b) C₆H₅N₂⁺BF₄⁻ →NaNO₂/Cu, Δ→ A →Fe/HCl→ B →CH₃COCl/pyridine→ C

(a) An organic compound (A) with the molecular formula C₉H₁₀O forms a 2,4-DNP derivative, reduces Fehling solution and undergoes Cannizzaro reaction. On vigorous oxidation it gives benzene-1,2-dicarboxylic acid.
(i) Identify compound (A) and write its IUPAC name.
(ii) Write the r …

(b)(i) Account for the following:
(1) The alpha (α) hydrogens of aldehydes and ketones are acidic in nature.
(2) Oxidation of aldehydes is easier than that of ketones.
(ii) Arrange the following:
(1) decreasing reactivity towards nucleophilic addition: propanal, acetone, benzalde …

(a)(i) Write the reaction involved in Cannizzaro's reaction.
(ii) Why are the boiling points of aldehydes and ketones lower than those of the corresponding carboxylic acids?
(iii) An organic compound 'A' with molecular formula C₅H₈O₂ is reduced to n-pentane with hydrazine followe …

(a) Write the product(s) of the three reactions shown in the figure.
(b) Give simple chemical tests to distinguish between the following pairs of compounds:
i) butanal and butan-2-one
ii) benzoic acid and phenol

(a) Write the reactions involved in the following:
i) Etard reaction ii) Stephen reduction
(b) How will you convert the following in not more than two steps?
i) benzoic acid to benzaldehyde
ii) acetophenone to benzoic acid
iii) ethanoic acid to 2-hydroxyethanoic acid

(a) Write the structures of A, B, C and D in the sequence shown in the figure.
(b) Distinguish between:
i) C₆H₅–CH=CH–COCH₃ and C₆H₅–CH=CH–COCH₂CH₃
ii) CH₃CH₂COOH and HCOOH
(c) Arrange the following in increasing order of their boiling points: CH₃CH₂OH, CH₃COCH₃, CH₃COOH.

(a) Write the chemical reaction involved in the Etard reaction.
(b) Arrange the following in increasing order of reactivity towards nucleophilic addition: CH₃CHO, C₆H₅COCH₃, HCHO.
(c) Why is the pKₐ of Cl–CH₂–COOH lower than the pKₐ of CH₃COOH?
(d) Write the product of the follow …

(a) Write the structures of A, B, C and D in the sequence shown in the figure (Delhi 2016).

a) Write the chemical equation for the reaction involved in the Cannizzaro reaction.
b) Draw the structure of the semicarbazone of ethanal.
c) Why is the pKₐ of F–CH₂–COOH lower than that of Cl–CH₂–COOH?
d) Write the product of the following reaction: …

i) Give chemical tests to distinguish between the following:
a) benzoic acid and ethyl benzoate
b) benzaldehyde and acetophenone
ii) Complete each synthesis shown in the figure (parts a, b, c) by giving the missing reagents or products.

i) Illustrate the following name reactions:
a) Cannizzaro reaction b) Clemmensen reduction
ii) How would you obtain the following?
a) but-2-enal from ethanal b) butanoic acid from butanol c) benzoic acid from ethylbenzene

i) Describe the following, giving linked chemical equations:
a) Cannizzaro reaction b) decarboxylation
ii) Complete the three chemical equations shown in the figure (parts a, b, c).

i) Give chemical tests to distinguish between:
a) propanal and propanone b) benzaldehyde and acetophenone
ii) How would you obtain:
a) but-2-enal from ethanal b) butanoic acid from butanal c) benzoic acid from ethylbenzene?

a) Illustrate the following name reactions:
i) Hell–Volhard–Zelinsky reaction ii) Wolff–Kishner reduction
b) How are the following conversions carried out?
i) ethyl cyanide to ethanoic acid ii) butan-1-ol to butanoic acid iii) methylbenzene to benzoic acid
Write chemical equation …

a) Illustrate the following name reactions, giving a chemical equation in each case:
i) Clemmensen reaction ii) Cannizzaro's reaction
b) Describe how the following conversions can be brought about:
i) cyclohexanol to cyclohexan-1-one ii) ethylbenzene to benzoic acid iii) bromoben …

a) Give chemical tests to distinguish between the following pairs of compounds:
i) ethanol and propanal ii) phenol and benzoic acid
b) How will you bring about the following conversions?
i) benzoic acid to benzaldehyde ii) ethanal to but-2-enal iii) propanone to propene
Give the …

a) Explain the mechanism of a nucleophilic attack on the carbonyl group of an aldehyde or a ketone.
b) An organic compound (A), molecular formula C₈H₁₆O₂, was hydrolysed with dilute sulphuric acid to give a carboxylic acid (B) and an alcohol (C). Oxidation of (C) with chromic aci …

a) How will you bring about the following conversions?
i) ethanol to 3-hydroxybutanal
ii) benzaldehyde to benzophenone
b) An organic compound A has the molecular formula C₈H₁₆O₂. It is hydrolysed by dilute sulphuric acid to a carboxylic acid B and an alcohol C. Oxidation of C wit …

a) Write chemical equations to illustrate the following name reactions:
i) Cannizzaro's reaction ii) aldol condensation
b) Give chemical tests to distinguish between the following pairs of compounds:
i) propanal and propanone ii) acetophenone and benzophenone

a) How are the following obtained?
i) benzoic acid from ethylbenzene
ii) benzaldehyde from toluene
b) Complete each synthesis by giving the missing material, reagent or product:
i) C₆H₅COCl →H₂/Pd–BaSO₄→ ____
ii), iii) (the two syntheses shown in the figure)

a) Illustrate the following name reactions giving a chemical equation in each case:
i) Clemmensen reaction ii) Cannizzaro's reaction
b) An organic compound contains 69.70% carbon, 11.63% hydrogen and the rest oxygen; molecular mass 86. It does not reduce Tollens' reagent, but for …

a) Complete the two reaction statements shown in the figure by giving the missing starting material, reagent or product.
b) Describe the following reactions:
i) Cannizzaro reaction ii) cross aldol condensation