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NEET & JEE · Chemistry · Class 12

Aldehydes Ketones and Carboxylic Acids — NEET Chemistry MCQs

30 questions written by hand against the NCERT chapter. Every wrong option is explained, not just the right one.

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Sample questions from this chapter

What is the geometry around a carbonyl carbon?
  1. Trigonal planar with approximately 120° bond angles ✓
  2. Tetrahedral with approximately 109.5° angles
  3. Linear with 180° angles
  4. Trigonal pyramidal with a carbon lone pair
Answer: A. The carbonyl carbon is sp2 hybridised and trigonal planar; nucleophilic addition converts it to a tetrahedral alkoxide. Using the product geometry for the reactant is the main trap.
Why not B: Carbonyl carbon is sp2 before nucleophilic addition, not sp3.
Why not C: sp hybridisation would be required for linear geometry.
Why not D: Carbonyl carbon has no lone pair and lies in the plane of its three sigma bonds.
What product forms when ethanal reacts with HCN?
  1. Ethanoic acid
  2. Ethanol
  3. 2-Hydroxypropanenitrile ✓
  4. Propanone
Answer: C. CN− attacks carbonyl carbon and protonation gives CH3CH(OH)CN, a cyanohydrin with one extra carbon. Ethanoic acid is the oxidation trap.
Why not A: This would be oxidation of the aldehyde.
Why not B: This would be reduction of the carbonyl.
Why not D: HCN adds C and N rather than converting the aldehyde into a ketone.
An unknown C8H8O compound gives 2,4-DNP and iodoform tests but not Tollens test. Vigorous oxidation gives benzoic acid. What is it?
  1. Acetophenone ✓
  2. Phenylacetaldehyde
  3. Methyl benzoate
  4. Ethylbenzene
Answer: A. C6H5COCH3 is an aromatic methyl ketone: DNP-positive, iodoform-positive, Tollens-negative, and side-chain oxidation yields benzoic acid. Phenylacetaldehyde is the aldehyde trap.
Why not B: An aldehyde should reduce Tollens reagent and its structure is not a methyl ketone.
Why not C: An ester does not give the ordinary 2,4-DNP carbonyl test or iodoform response.
Why not D: A hydrocarbon lacks the carbonyl detected by 2,4-DNP.

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Read the chapter first

Every NCERT question in this chapter is solved, free: NCERT solutions — Aldehydes Ketones and Carboxylic Acids →

Other NEET Chemistry chapters

Some Basic Concepts of ChemistryStructure of AtomClassification of Elements and Periodicity in PropertiesChemical Bonding and Molecular StructureThermodynamicsEquilibrium

All 19 chapters →

Questions

How many NEET questions are there on Aldehydes Ketones and Carboxylic Acids?

This chapter test has 30 questions — 10 easy, 14 medium and 6 hard — all written against the NCERT Class 12 chapter.

Is this NEET Chemistry chapter test free?

Yes. Every chapter test is free with no login, and you get your all-India rank on every one. Nothing on the site is on sale right now.

Do the questions explain the wrong options?

Yes — every distractor carries its own explanation naming the specific misconception that makes a student pick it. That is the part most question banks skip, and it is the part that changes your next attempt.