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Aldehydes and Ketones - ISC Class 12 Chemistry Questions with Answers, Page 3

56 past-paper questions on Aldehydes and Ketones from ISC Class 12 Chemistry papers (2027-2018), newest first, in full. Questions 41-56 are on this page, 20 to a page. Tap "Show answer" under a question to see its answer.

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2023 · 4 marks · Fill inOpen: Fill in the blanks by choosing the appropriate word(s) from those given in the…
Fill in the blanks by choosing the appropriate word(s) from those given in the brackets: [two, Williamson’s synthesis, three, anisole, toluene, Friedel-Crafts alkylation, iodoform, sec-1, mol-1L sec-1, Lewis base, acetone, Lewis acid, chloroform, formaldehyde]
(i)[1.0]
Sodium phenoxide reacts with methyl chloride to give ____. The reaction is known as ____.
(ii)[1.0]
When the concentration of a reactant of first order reaction is tripled, the rate of reaction becomes ____ times. The unit of rate constant ($k$) for the first order reaction is ____.
(iii)[1.0]
In coordination complexes, the central metal atom or ion behaves as ____ and the ligands behave as ____.
(iv)[1.0]
Calcium acetate on dry distillation gives ____ which gives ____ on heating with iodine and alkali.

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2023 · 2 marks · Short answerOpen: An aromatic carboxylic acid [A] which readily sublimes on heating, produces…
An aromatic carboxylic acid [A] which readily sublimes on heating, produces compound [B] on treatment with $\text{PCl}_5$. Compound [B], when reduced in the presence of $\text{Pd}$ catalyst over $\text{BaSO}_4$ poisoned by sulphur in xylene solution gives compound [C]. When compound [C] is condensed in the presence of alcoholic $\text{KCN}$, it gives compound [D]. (Molecular formula of compound [D] is $\text{C}_{14}\text{H}_{12}\text{O}_2$) Identify the compounds [A], [B], [C] and [D].

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2023 · 5 marks · Short answerOpen: Starting with methyl magnesium bromide, how will the following compounds be…
(i)[3.0]
Starting with methyl magnesium bromide, how will the following compounds be synthesised? (a) Acetaldehyde (b) Acetone (c) Acetic acid
(ii)[2.0]
Explain the following: (a) Chloroacetic acid is stronger acid than acetic acid. (b) Formic acid reduces Tollen’s reagent but acetic acid does not.

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2022 · 3 marks · Fill inOpen: Fill in the blanks by choosing the appropriate word(s) from those given in the…
Fill in the blanks by choosing the appropriate word(s) from those given in the brackets: (two, four, $\text{sec}^{-1}$, diamagnetic, acetaldehyde, $\text{mol}^{-1}\text{L }\text{sec}^{-1}$, paramagnetic, formaldehyde, acetone, ethanol)
(i)[1.0]
When the concentration of a reactant of first order reaction is doubled, the rate of reaction becomes ___________ times. The unit of rate constant ($k$) for the first order reaction is ___________.
(ii)[1.0]
The transition metals show ___________ character because of the presence of unpaired electrons while $\text{Cu}^+$ is ___________ because its electronic configuration is $[\text{Ar}]3d^{10}$.
(iii)[1.0]
Calcium formate on distillation gives ___________ but the distillation of calcium formate and calcium acetate gives ___________.

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2020 · 3 marks · Short answerOpen: A ketone A ( ) which undergoes Iodoform reaction gives compound B on reduction…
A ketone A ($\text{C}_4\text{H}_8\text{O}$) which undergoes Iodoform reaction gives compound B on reduction. B on heating with $\text{conc. H}_2\text{SO}_4$ at $443\text{ K}$ gives a compound C which forms ozonide D. D on hydrolysis with Zn dust gives only E. Identify the compounds A to E. Write the Iodoform reaction with compound A.

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2019 · 5 marks · Short answerOpen: Write chemical equations to illustrate the following name reactions: (1) Aldol…
(i)
Write chemical equations to illustrate the following name reactions: (1) Aldol condensation. (2) Cannizzaro’s reaction. (3) Benzoin condensation.
(ii)
Identify the compounds A and B in the given reactions: (1) $\text{Benzene} \xrightarrow[\text{anhydrous AlCl}_3]{\text{CH}_3\text{Cl}} \text{A} \xrightarrow{\text{alk. KMnO}_4} \text{B}$ (2) $\text{CH}_3\text{COCH}_3 \xrightarrow[\text{HNO}_3\text{ (conc.)}]{[\text{O}]} \text{A} \xrightarrow{\text{PCl}_5} \text{B}$

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2019 · 5 marks · Short answerOpen: Give balanced chemical equations for the following reactions: (1) Acetaldehyde…
(i)
Give balanced chemical equations for the following reactions: (1) Acetaldehyde reacts with hydrogen cyanide. (2) Acetone reacts with phenyl hydrazine. (3) Acetic acid is treated with ethanol and a drop of conc. $\text{H}_2\text{SO}_4$.
(ii)
Give one chemical test each to distinguish between the following pairs of compounds: (1) Acetone and benzaldehyde. (2) Phenol and benzoic acid.

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2018 · 5 marks · Short answerOpen: Write the product(s) of the following reactions: (1) (2) (3) Give one chemical…
(i)[3.0]
Write the product(s) of the following reactions: (1) $\text{CH}_3\text{COCH}_3 + \text{H}_2\text{NOH} \rightarrow$ (2) $2\text{ C}_6\text{H}_5\text{CHO} + \text{conc. NaOH} \rightarrow$ (3) $\text{CH}_3\text{COOH} \xrightarrow{\text{Cl}_2/\text{P}}$
(ii)[2.0]
Give one chemical test each to distinguish between the following pairs of compounds: (1) Benzaldehyde and Benzoic acid (2) Propanal and Propanone

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2018 · 5 marks · Short answerOpen: Write chemical equations to illustrate the following name reactions: (1)…
(i)
Write chemical equations to illustrate the following name reactions: (1) Clemmensen’s reduction (2) Rosenmund’s reduction (3) HVZ reaction
(ii)
Explain why: (1) Acetaldehyde undergoes aldol condensation, but formaldehyde does not. (2) Acetic acid is a weaker acid as compared to formic acid.

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2018 · 5 marks · Short answerOpen: Write the chemical equations to illustrate the following name reactions: (1)…
(i)[3.0]
Write the chemical equations to illustrate the following name reactions: (1) Wolff-Kishner reduction. (2) Aldol condensation. (3) Cannizzaro reaction.
(ii)[2.0]
Account for the following: (1) $\text{CH}_3\text{CHO}$ is more reactive with $\text{HCN}$ than $\text{CH}_3\text{COCH}_3$. (2) Carboxylic acids are stronger acids than phenol.

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2018 · 5 marks · Short answerOpen: Give balanced equations for the following reactions: (1) Benzaldehyde reacts…
(i)
Give balanced equations for the following reactions: (1) Benzaldehyde reacts with hydrazine. (2) Acetic acid reacts with phosphorous pentachloride. (3) Acetone reacts with sodium bisulphite.
(ii)
Give one chemical test each to distinguish between the following pairs of compounds: (1) Ethanol and acetic acid (2) Acetaldehyde and benzaldehyde

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