Aldehydes and Ketones carries 4.0 of 100 Chemistry marks in NEET by past-paper share: 28 of the 707 tagged NEET Chemistry PYQs in the ViJEEta bank (NEET 2013–2026). It ranks 12 of 26 Chemistry chapters.
How the weight is computed: this chapter's tagged NEET PYQs divided by all tagged NEET Chemistry PYQs in the bank (28 of 707), times 100, with repeated questions counted once. The bank does not store the year of each NEET question, so none is printed. Computed from the bank at build time. Updated 19 Oct 2026.
16 facts the paper keeps asking, each with how it is asked. Copy it onto one page of your notebook: that page is this chapter's handbook.
Carbonyl carbon is and trigonal coplanar (); the C is the electrophilic (Lewis acid) centre and the O is the nucleophilic (Lewis base) centre
Asked as: hybridisation of carbonyl C before and after nucleophilic attack (, tetrahedral alkoxide intermediate)
Ethyne + () gives acetaldehyde; every other alkyne gives a ketone
Asked as: which alkyne gives an aldehyde on hydration
Rosenmund: acyl chloride + over gives an aldehyde. Stephen: nitrile + gives an imine, which hydrolyses to an aldehyde. DIBAL-H reduces nitriles and esters to aldehydes
Asked as: match the named reaction to its reagent, or pick the reagent for ethanenitrile ethanal
Etard: toluene + , then hydrolysis, gives benzaldehyde. Gatterman-Koch: benzene + + (anhyd. ) gives benzaldehyde
Asked as: name the reaction from its reagent pair
Ketones are made from acyl chloride + dialkylcadmium, from nitrile + Grignard then hydrolysis, and from benzene + acid chloride with anhyd. (Friedel-Crafts acylation)
Asked as: reagent that turns an acyl chloride into a ketone (dialkylcadmium, from + Grignard reagent)
Boiling points at mass 58-60: n-butane methoxyethane propanal acetone propan-1-ol . Carbonyls show dipole-dipole forces but no H-bonding among themselves
Asked as: arrange in increasing b.p. (alkane ether aldehyde alcohol)
In nucleophilic addition, aldehydes are more reactive than ketones for steric and electronic reasons. Benzaldehyde is less reactive than propanal because resonance lowers its polarity
Asked as: order Butanone Propanone Propanal Ethanal
adds through base catalysis ( is the nucleophile) to give cyanohydrins. The adduct equilibrium lies to the right for most aldehydes and to the left for most ketones, so the adduct is used to separate and purify aldehydes
Asked as: why does the reaction with pure need a base, or why is bisulphite used for aldehydes
adds to of aldehydes and ketones under acid catalysis to give : gives an oxime, a hydrazone, and semicarbazide a semicarbazone. 2,4-DNP derivatives are yellow, orange or red solids
Asked as: match the reagent to the derivative; 2,4-DNP derivatives characterise aldehydes and ketones
is reduced to by Clemmensen ( + conc. ) or Wolff-Kishner (, then in ethylene glycol). give alcohols from aldehydes and alcohols from ketones
Asked as: which reagent turns a ketone into an alkane in acid medium and which in base medium
Tollens' (ammoniacal ) gives a silver mirror. Fehling's = Fehling A (aqueous ) + Fehling B (alkaline sodium potassium tartrate, Rochelle salt), mixed in equal amounts; it gives a reddish brown precipitate. Aromatic aldehydes do not respond to Fehling's test
Asked as: which test separates benzaldehyde from an aliphatic aldehyde
Haloform/iodoform: or groups react with to give a haloform plus the acid salt with one carbon fewer. A in the molecule is not affected
Asked as: which compound gives a yellow precipitate with (e.g. pentan-2-one gives it, pentan-3-one does not)
Aldol: a compound with at least one -H, in dilute alkali, gives a -hydroxy aldehyde or ketone, which loses water to give an -unsaturated carbonyl. A cross aldol between two partners that both have -H gives four products
Asked as: number of products from ethanal + propanal (4)
Cannizzaro: an aldehyde with no -H, in concentrated alkali, disproportionates; one molecule becomes an alcohol and the other a carboxylic acid salt
Asked as: which of , benzaldehyde, 2-methylpentanal undergoes Cannizzaro
values: , benzoic , acetic , phenol , ethanol . Carboxylate has two equivalent resonance forms with the charge on O. EWGs raise acidity, EDGs lower it: acidity order 4-methoxybenzoic ( ) benzoic () 4-nitrobenzoic ()
Asked as: arrange in acid strength, or explain why phenoxide's extra resonance forms still lose to carboxylate
is reduced to a alcohol by , or better by diborane; does not reduce it. HVZ: an acid with an -H + and red P gives an -halo acid
Asked as: which reagent reduces an aldehyde but leaves untouched; name the -halogenation reaction
Students mix up aldol and Cannizzaro. Aldol needs at least one α-H and works in dilute alkali. Cannizzaro needs no α-H and works in concentrated alkali (HCHO and benzaldehyde, for example). The aldol product is β-hydroxy, not α-hydroxy.
3 real previous-year questions from this chapter, as printed in the paper, each with its worked solution. Answer the first one here with no sign-in.
Correct answer: Option B
Correct answer: Option A
Correct answer: Option D
All 6 topics, by tagged PYQs, then practice questions. Counted from the bank. Updated 19 Oct 2026.
| Topic | PYQs | Practice questions |
|---|---|---|
| Chemical Properties of Carbonyl Compounds | 17 | 262 |
| Tests of Carbonyl Compounds | 5 | 86 |
| Preparation of Carbonyl Compounds | 4 | 64 |
| Introduction to Carbonyl Compounds | 1 | 28 |
| Physical Properties of Carbonyl Compounds | 1 | 7 |
| Miscellaneous Examples | 0 | 2 |
Unknown is not zero. Until you answer at least 3 graded questions in Aldehydes and Ketones, ViJEEta shows – instead of a zero or a 50% default. Book exercises can raise chapter mastery up to 0.60, adaptive practice up to 0.75, and only a timed chapter test or mock can certify 0.80 and above.
Every chapter test is 25 questions. It starts at moderate difficulty and adapts after each saved answer. If you open a solution before answering, that attempt earns no credit, so your mastery stays honest.
Start the Aldehydes and Ketones test