Aldehydes Ketones Practice Questions NEET: 15 MCQs

Which aldehydes and ketones practice block should you start with?

The best aldehydes ketones practice questions NEET block depends on whether concepts, reagents or multi-step applications cause your errors. Attempt all 15 MCQs once without notes, then repeat only the weakest five-question block. Every question is single-correct. Use NEET marking: +4 for correct, -1 for wrong and 0 for unattempted.

This set does not claim that aldehydes and ketones have a fixed number of NEET questions or guaranteed weightage. It is a diagnostic chapter drill, not a paper prediction.

1. Complete all 15 questions in one sitting.
2. Mark every answer that involved guessing.
3. Calculate your total out of 60.
4. Calculate separate scores out of 20 for Blocks A, B and C.
5. Revise and repeat only the lowest-scoring block.

Which aldehydes and ketones practice block should you choose?

Choose Block A for structure and reactivity errors, Block B for reagent-product confusion, and Block C for tests and short conversions. These are diagnostic practice categories, not official NTA sections or a prediction of chapter-wise distribution.

• Concepts tested
• Block A: Carbonyl structure, nucleophilic addition, relative reactivity, electronic effects and steric effects.
• Block B: Oxidation, reduction, aldol, Cannizzaro, Clemmensen and Wolff–Kishner outcomes.
• Block C: Tollens’, Fehling’s and iodoform-type distinctions, plus short reaction sequences.
• Typical mistake exposed
• Block A: Ranking compounds from memory without checking alkyl groups and crowding near the carbonyl carbon.
• Block B: Recognising the reagent but predicting the wrong product.
• Block C: Remembering individual reactions but choosing the wrong test or sequence.
• Calculation or reasoning load
• Block A: Low calculation, high structural reasoning.
• Block B: Medium reasoning, mainly product prediction.
• Block C: Medium to high application load because similar compounds must be separated logically.
• Best attempt order
• Block A: First if the chapter still feels conceptually uncertain.
• Block B: After carbonyl reactivity is clear.
• Block C: Last because it combines reactions and observations.
• What to revise after a low score
• Block A: Carbonyl polarity, nucleophilic-addition mechanism, steric effect and positive inductive effect.
• Block B: A reagent-condition-product table.
• Block C: Positive and negative test results, followed by two-step conversions.

Who should pick each aldehydes and ketones practice block first?

Pick the block that matches your recent mistakes. A student who cannot rank carbonyl compounds has a different problem from one who knows the reagent name but changes the wrong functional group. Use your wrong and guessed responses as evidence.

• Pick Block A first if you cannot rank carbonyl compounds by nucleophilic-addition reactivity or confuse electronic and steric effects.
• Pick Block B first if you remember reagent names but repeatedly predict the wrong product.
• Pick Block C first if individual reactions are manageable but distinction tests and two-step conversions cause errors.
• Class 11 students studying ahead should begin with Block A.
• Class 12 students after completing the chapter should attempt A, B and C in order.
• Droppers should attempt all 15 in one sitting and classify every error as concept, reagent recall or application.

Blind guessing is costly. An incorrect NEET response loses 1 mark, while an unattempted response gets 0. Guess only after eliminating options through chemistry.

Can you solve Block A on carbonyl structure and reactivity?

These five questions test why aldehydes and ketones undergo nucleophilic addition before moving to reagent outcomes. Check carbonyl polarisation, the number of electron-releasing alkyl groups and crowding around the carbonyl carbon.

Which options are correct for Questions 1 to 5?

1. Which is the correct decreasing order of reactivity towards nucleophilic addition?

• A.

• B.

• C.

• D.

2. Which statement correctly describes the carbonyl group?

• A. Carbon is partially negative and oxygen is partially positive.
• B. Both carbon and oxygen are partially negative.
• C. Carbon is partially positive and oxygen is partially negative.
• D. The carbon-oxygen bond is non-polar.

3. Why is ethanal generally more reactive than propanone towards nucleophilic addition?

• A. Ethanal has two alkyl groups attached to its carbonyl carbon.
• B. Propanone has less steric crowding and a weaker positive inductive effect.
• C. Ethanal has less steric crowding and only one electron-releasing alkyl group.
• D. Ketones cannot undergo nucleophilic addition.

4. What is formed when propanone reacts with hydrogen cyanide?

• A. $\mathrm{C}{\mathrm{H}}_3\mathrm{C}{\mathrm{H}}_2\mathrm{C}{\mathrm{H}}_2\mathrm{C}\mathrm{N}$
• B. $(\mathrm{C}{\mathrm{H}}_3{)}_2\mathrm{C}(\mathrm{O}\mathrm{H})\mathrm{C}\mathrm{N}$
• C. $\mathrm{C}{\mathrm{H}}_3\mathrm{C}\mathrm{H}(\mathrm{O}\mathrm{H})\mathrm{C}{\mathrm{H}}_2\mathrm{C}\mathrm{N}$
• D. $(\mathrm{C}{\mathrm{H}}_3{)}_2\mathrm{C}\mathrm{H}\mathrm{C}\mathrm{N}$

5. Which product is formed when ethanal reacts with sodium hydrogen sulphite?

• A. $\mathrm{C}{\mathrm{H}}_3\mathrm{C}\mathrm{H}(\mathrm{O}\mathrm{H})\mathrm{S}{\mathrm{O}}_3\mathrm{N}\mathrm{a}$
• B. $\mathrm{C}{\mathrm{H}}_3\mathrm{C}{\mathrm{H}}_2\mathrm{S}{\mathrm{O}}_3\mathrm{N}\mathrm{a}$
• C. $\mathrm{C}{\mathrm{H}}_3\mathrm{C}\mathrm{O}\mathrm{O}\mathrm{N}\mathrm{a}$
• D. $\mathrm{C}{\mathrm{H}}_3\mathrm{C}{\mathrm{H}}_2\mathrm{O}\mathrm{H}$

Can you solve Block B on reagents and named reactions?

These five aldehydes ketones practice questions NEET problems test product prediction rather than reagent-name recall. Before choosing, check for an alpha hydrogen, identify acidic or basic conditions, and decide whether the carbonyl group is oxidised, reduced or used to form a carbon-carbon bond.

Which options are correct for Questions 6 to 10?

1. Which compound undergoes self-aldol addition with dilute sodium hydroxide?

• A. Methanal
• B. Benzaldehyde
• C. Ethanal
• D. Benzophenone

2. Benzaldehyde is treated with concentrated sodium hydroxide. Which products form?

• A. Benzyl alcohol and sodium benzoate
• B. Benzoic acid and methanol
• C. Benzene and sodium formate
• D. Benzophenone and water

3. Which comparison of Clemmensen and Wolff–Kishner reductions is correct?

• A. Both require strongly acidic conditions.
• B. Clemmensen uses zinc amalgam and hydrochloric acid, while Wolff–Kishner uses hydrazine, potassium hydroxide and heat.
• C. Clemmensen oxidises ketones, while Wolff–Kishner reduces aldehydes only.
• D. Both convert a carbonyl compound into an alcohol.

4. A mixture contains propanal and propanone. Which reagent selectively oxidises propanal under the test conditions?

• A. Tollens’ reagent
• B. Hydrogen with nickel
• C. Sodium borohydride
• D. Lithium aluminium hydride

5. Ethanal is treated first with dilute sodium hydroxide and then heated. What is the major final product?

• A. $\mathrm{C}{\mathrm{H}}_3\mathrm{C}\mathrm{H}(\mathrm{O}\mathrm{H})\mathrm{C}{\mathrm{H}}_2\mathrm{C}\mathrm{H}\mathrm{O}$
• B. $\mathrm{C}{\mathrm{H}}_3\mathrm{C}\mathrm{H}=\mathrm{C}\mathrm{H}\mathrm{C}\mathrm{H}\mathrm{O}$
• C. $\mathrm{C}{\mathrm{H}}_3\mathrm{C}{\mathrm{H}}_2\mathrm{C}{\mathrm{H}}_2\mathrm{C}\mathrm{H}\mathrm{O}$
• D. $\mathrm{C}{\mathrm{H}}_3\mathrm{C}\mathrm{O}\mathrm{C}{\mathrm{H}}_2\mathrm{C}{\mathrm{H}}_3$

Can you solve Block C on identification tests and conversions?

These five questions test observations, compound discrimination and short reaction sequences. Decide whether the compound is an aldehyde or ketone, whether an aldehyde is aliphatic or aromatic, and whether it contains the structural unit needed for the iodoform test.

Which options are correct for Questions 11 to 15?

1. Which observation distinguishes propanal from propanone using Tollens’ reagent?

• A. Propanal gives a silver mirror, while propanone does not.
• B. Propanone gives a silver mirror, while propanal does not.
• C. Both give a silver mirror.
• D. Both produce a yellow precipitate.

2. Which result is expected with Fehling’s solution?

• A. Both ethanal and benzaldehyde give a red precipitate.
• B. Ethanal gives a red precipitate, while benzaldehyde generally does not.
• C. Benzaldehyde gives a red precipitate, while ethanal does not.
• D. Both produce a silver mirror.

3. Which pair gives a positive iodoform test?

• A. Methanal and benzaldehyde
• B. Ethanal and propanone
• C. Propanal and benzophenone
• D. Benzaldehyde and propanal

4. Which reagent best distinguishes acetophenone from benzophenone?

• A. Iodine and sodium hydroxide
• B. Tollens’ reagent
• C. Fehling’s solution
• D. Acidified potassium dichromate

5. Which sequence converts ethanol first into ethanal and then into ethanoic acid?

• A. PCC, followed by acidified potassium dichromate
• B. Sodium borohydride, followed by PCC
• C. Hydrogen with nickel, followed by Tollens’ reagent
• D. Zinc amalgam with hydrochloric acid, followed by dilute sodium hydroxide

If the alcohol-to-carbonyl step caused trouble, solve Alcohols Phenols Ethers Practice Questions NEET: 15 MCQs after completing this diagnosis.

What are the answers, worked explanations and next practice steps?

Score the set only after completing all 15 questions. The maximum raw score is 60 because this article has 15 questions worth 4 marks each. This is a practice score, not official chapter weightage or a prediction of how many aldehyde and ketone questions will appear.

What is the complete answer key?

• 1. A
• 2. C
• 3. C
• 4. B
• 5. A
• 6. C
• 7. A
• 8. B
• 9. A
• 10. B
• 11. A
• 12. B
• 13. B
• 14. A
• 15. A

Why is each answer correct?

1. A: Formaldehyde has no alkyl groups and the least crowding. Aldehydes are generally more reactive than comparable ketones. Benzophenone is crowded, and conjugation with its phenyl groups lowers the electrophilicity of the carbonyl carbon.
2. C: Oxygen attracts the bonding electrons more strongly. Oxygen becomes partially negative, while carbon becomes partially positive. Option A reverses this polarisation.
3. C: Ethanal has one electron-releasing alkyl group, while propanone has two. Propanone therefore has greater crowding and a stronger positive inductive effect. Option D is wrong because ketones do undergo nucleophilic addition.
4. B: Cyanide attacks the carbonyl carbon, and protonation produces the cyanohydrin. $(\mathrm{C}{\mathrm{H}}_3{)}_2\mathrm{C}(\mathrm{O}\mathrm{H})\mathrm{C}\mathrm{N}$

Option D wrongly removes the oxygen atom.

5. A: Sodium hydrogen sulphite undergoes nucleophilic addition across the carbonyl group. $\mathrm{C}{\mathrm{H}}_3\mathrm{C}\mathrm{H}(\mathrm{O}\mathrm{H})\mathrm{S}{\mathrm{O}}_3\mathrm{N}\mathrm{a}$

The reaction is neither oxidation nor reduction.

6. C: Ethanal has alpha hydrogens and undergoes self-aldol addition. Methanal and benzaldehyde lack alpha hydrogens. Benzophenone also has no alpha hydrogen.
7. A: Benzaldehyde has no alpha hydrogen, so concentrated base causes Cannizzaro disproportionation. One molecule is reduced to benzyl alcohol, while another is oxidised to sodium benzoate.
8. B: Clemmensen reduction uses acidic conditions with zinc amalgam and hydrochloric acid. Wolff–Kishner reduction uses hydrazine, strong base and heat. Both convert the carbonyl group into a methylene group, not an alcohol.
9. A: Tollens’ reagent oxidises propanal but not ordinary propanone under the test conditions. The other three options are reducing agents.
10. B: Dilute base first produces 3-hydroxybutanal. Heating removes water and forms crotonaldehyde. $\mathrm{C}{\mathrm{H}}_3\mathrm{C}\mathrm{H}=\mathrm{C}\mathrm{H}\mathrm{C}\mathrm{H}\mathrm{O}$

Option A is the aldol product before heating.

11. A: Propanal reduces Tollens’ reagent and produces a silver mirror. Propanone is an ordinary ketone and gives a negative result.
12. B: Aliphatic aldehydes such as ethanal reduce Fehling’s solution to a red precipitate. Benzaldehyde generally does not give this test. A silver mirror is associated with Tollens’ reagent, not Fehling’s solution.
13. B: Propanone is a methyl ketone, and ethanal also gives the iodoform test. The other aldehydes and benzophenone lack the required structural unit.
14. A: Acetophenone is a methyl ketone and gives a yellow iodoform precipitate with iodine and sodium hydroxide. Benzophenone has no methyl group attached to its carbonyl carbon. Tollens’ and Fehling’s reagents are negative for both ketones.
15. A: Controlled PCC oxidation converts ethanol into ethanal. Further oxidation with acidified potassium dichromate produces ethanoic acid. The reducing agents in the other options cannot complete this sequence.

What should you revise from your block-wise score?

Treat guessed answers as unresolved even when they happen to be correct.

• Repeated Block A errors: Revise carbonyl polarity, nucleophilic attack, relative reactivity, positive inductive effects and steric effects.
• Repeated Block B errors: Make a reagent-condition-product table. Keep acidic Clemmensen conditions separate from basic Wolff–Kishner conditions.
• Repeated Block C errors: Practise distinction logic. For each test, write the reagent, positive compound, observation and chemical reason.

Chemistry has 45 compulsory questions within the 180-question, 180-minute NEET paper. This chapter drill is not a prediction of chapter-wise distribution. For a worked application involving oxygen-containing organic compounds, use Organic Compounds Containing Oxygen NEET 2026: Full Solution without treating one solved question as a guaranteed future pattern.

After revision, redo only the incorrect and guessed questions. Do not immediately reread every solution, because recognising an answer is easier than predicting the product independently.