MCQ ON ALDEHYDES & KETONES

Which of the following will fail to react with potassium dichromate and dilute sulphuric acid (a) Ethyl alcohol (ethanol) (b) Acetaldehyde (ethanal) (c) Secondary propyl alcohol (2-propanol) (d) Acetone (propanone) Acetone and acetaldehyde are differentiated by [CPMT 1987, 93] (a) (b) (c) (d) Which of the following will react with water [IIT 1998] (a) (b) (c) (d) An organic compound ‘A’ has the molecular formula it undergoes iodoform test. When saturated with dil. is gives ‘B’ of molecular formula . A and B respectively are [Tamil Nadu CET 2002] (a) Propanal and mesitylene (b) Propanone and mesityl oxide (c) Propanone and 2,6–dimethyl –2, 5-heptadien–4–one (d) Propanone and mesitylene oxide Which alkene is formed from the following reaction [Manipal 2001] (a) 3- Methyl-3-heptene (b) 4-Methyl-3-heptene (c) 5-Methyl-3-heptene (d) 1-Methyl-5- methane Compound ‘A’ (molecular formula is treated with acidified potassium dichromate to form a product ‘B’ (molecular formula ‘B’ forms a shining silver mirror on warming with ammoniacal silver nitrate. ‘B’ when treated with an aqueous solution of and sodium acetate gives a product ‘C’. Identify the structure of ‘C’ [IIT-JEE (Screening) 2002] (a) (b) (c) (d) Which is not true about acetophenone [Manipal 2002] (a) Reacts to form 2, 4-dinitorphenyl hydrazine (b) Reacts with Tollen’s reagent to form silver mirror (c) Reacts with to form iodoform (d) On oxidation with alkaline followed by hydrolysis gives benzoic acid The enol form of acetone, after treatment with gives [IIT-JEE (Screening) 1999] (a) (b) (c) (d) The appropriate reagent for the transformation [IIT-JEE (Screening) 2000] (a) (b) (c) (d) Which of the following has the most acidic hydrogen [IIT-JEE (Screening) 2000] (a) 3-hexanone (b) 2, 4-hexanedione (c) 2, 5-hexanedione (d) 2, 3-hexanedione Which of the following will be most readily dehydrated in acidic conditions [IIT-JEE (Screening) 2000] (a) (b) (c) (d) Major Product is [IIT-JEE (Screening) 2003] (a) (b) (c) (d) Among the given compounds, the most susceptible to nucleophilic attack at the carbonyl group is [IIT 1997] (a) MeCOCl (b) MeCHO (c) MeCOOMe (d) MeCOOCOMe Which of the following will give yellow precipitate with [IIT 1997] (a) (b) (c) (d) The product of acid hydrolysis of P and Q can be distinguished by [IIT-JEE (Screening) 2003] (a) Lucas Reagent (b) 2,4-DNP (c) Fehling’s Solution (d) On vigorous oxidation by permanganate solution gives [AIEEE 2002] (a) (b) (c) (d) Which of the following reactions give benzo phenone [Roorkee Qualifying 1998] (a) (b) (c) (d) Aldehyde and ketones can decolourize by [CPMT 2003] (a) Bromine water (b) Quick lime (c) dil. (d) None of these Which of the following statements regarding chemical properties of acetophenone are wrong (1) It is reduced to methyl phenyl carbinol by sodium and ethanol (2) It is oxidised to benzoic acid with acidified (3) It does not undergo iodoform electrophilic substitution like nitration at meta position (4) It does not undergo iodoform reaction with iodine and alkali [Tamil Nadu CET 2001] (a) 1 and 2 (b) 2 and 4 (c) 3 and 4 (d) 1 and 3 The product(s) obtained via oxymercuration of 1-butyne would be [IIT-JEE 1999] (a) (b) (c) (d) The most reactive compound towards formation of cyanohydrin on treatment with KCN followed by acidification is [GATE 2001] (a) Benzaldehyde (b) p-Nitrobenzaldehyde (c) Phenyl acetaldehyde (d) p-Hydroxybenzaldehyde The key step in cannizzaro’s reaction is the intermolecular shift of [Orissa JEE 2003] (a) Proton (b) Hydride ion (c) Hydronium ion (d) Hydrogen bond Benzophenone does not react with [BHU 2003] (a) (b) (c) (d) The most suitable reagent for the conversion of is [AIIMS 2004] (a) (b) (c) (d) PCC (Pyridine chloro chromate) The conversion of acetophenone to acetanilide is best accomplished by using : [UPSEAT 2004] (a) Backmann rearrangement (b) Curtius rearrangement (c) Lossen rearrangement (d) Hofmann rearrangement Which of the following will not give iodoform test ? [UPSEAT 2004] (a) Isopropyl alcohol (b) Ethanol (c) Ethanal (d) Benzyl alcohol The compound (X) is [IIT-JEE 2005] (a) (b) (c) (d) The major organic product formed from the following reaction [CBSE PMT 2005] (a) (b) (c) (d) Products of the following reaction [CBSE PMT 2005] (a) (b) (c) (d) A compound, containing only carbon, hydrogen and oxygen, has a molecular weight of 44. On complete oxidation it is converted into a compound of molecular weight 60. The original compound is [KCET 2005] (a) An aldehyde (b) An acid (c) An alcohol (d) an ether Benzophenone can be converted into benzene using [Tamil Nadu CET 2001] (a) Fused alkali (b) Anhydrous (c) Sodium amalgam in water (d) Acidified dichromate The reagent(s) which can be used to distinguish acetophenone from benzophenone is (are) [CBSE PMT 1990] (a) 2, 4-dinitrophenyl hydrazine (b) Aqueous solution of (c) Benedict reagent (d) and When acetaldehyde is heated with Fehling solution, it gives a red precipitate of [MP PET 1989, 93; IIT 1982; MP PET/PMT 1998; RPMT 2002] (a) (b) (c) (d) The general order of reactivity of carbonyl compounds for nucleophilic addition reactions is [CBSE PMT 1995] (a) (b) (c) (d) Which of the following gives an alcohol and salt of carboxylic acid when reacted with conc. NaOH [MP PMT 1999] (a) (b) (c) (d) Which of the following compounds would undergo Cannizzaro's reaction [CPMT 1989; AFMC 1991; MNR 1995] (a) Propionaldehyde (b) Benzaldehyde (c) Bromobenzene (d) Acetaldehyde reacts with [BHU 2003] (a) (b) (c) (d) The product of following reaction [Kerala CET 2000] (a) (b) (c) (d) Which of the following aldehydes is most reactive towards nucleophilic addition reactions [Roorkee 1992; RPMT 1997] (a) HCHO (b) (c) (d) Which one of the following gives iodoform test [AIIMS 1996] (a) Formaldehyde (b) Ethyl alcohol (c) Benzyl alcohol (d) Benzaldehyde The active ion in Tollen's reagent is (a) (b) (c) (d) Among the following compounds, which will react with acetone to give a product containing [IIT 1998] (a) (b) (c) (d) Which of the following does not give yellow precipitate with and NaOH [MP PET 1996] (a) (b) (c) (d) HCHO In this reaction an asymmetric centre is generated. The acid obtained would be [CBSE PMT 2003] (a) 20% D + 80% L-isomer (b) D-isomer (c) L-isomer (d) 50% D + 50% L-isomer Aldehydes are produced in atmosphere by [NCERT 1982] (a) Oxidation of secondary alcohols (b) Reduction of alkenes (c) Reaction of oxygen atoms with hydrocarbons (d) Reaction of oxygen atoms with ozone Which of the following compounds will give positive test with Tollen's reagent [CBSE PMT 1994; Kurukshetra CEE 1998; AFMC 2002] (a) Acetamide (b) Acetaldehyde (c) Acetic acid (d) Acetone is an example of (a) Friedel-Craft's alkylation (b) Friedel-Craft's acylation (c) Cannizzaro reaction (d) Claisen condensation Which of the following fails to answer the iodoform test. [CBSE PMT 1989] (a) Pentanone–1 (b) Pentanone–2 (c) Propanone–2 (d) Ethanol The reagent used for the separation of acetaldehyde from acetophenone is [AIIMS 2004] (a) (b) (c) (d)  1. (d) Acetone oxidise by & conc. into carboxylic acid. It is not oxidised by dilute . 2. (b) Acetaldehyde react with tollen's reagent while ketone do not react with tollen's reagent. 3. (b) 4. (c) The compound A with formula gives iodoform test, it is propanone forms a compound B having carbon atoms three times, the number of carbon atoms in propanone, it is 2, 6-dimethyl-2, 5-heptadien-4-one. 5. (a) 6. (a) 7. (b) Acetophenone is a ketone and does not react with Tollen’s reagent to give silver mirror. 8. (b) ⇌ ⇌ ⇌ ⇌ The enol form of acetone on treatment with undergoes enolisation, deutration (addition of ) and dehydration (removal of ). The repeated enolisation, deutration and dehydration ultimately gives . 9. (b) Both and can reduce group to group, but HCl will also bring about dehydration of alcohol to form alkene. Therefore, appropriate reagent for the conversion is . 10. (b) 2, 4-hexanedione (a 1, 3-diketone) has the most acidic hydrogen. This is because the carbanion left after the removal of is resonance stabilised in this case. 11. (a) Aldols ((-hydroxy aldehydes or (-hydroxyketones) readily undergo dehydration to form (, (-unsaturated aldehydes or ketones. 12. (b) 13. (a) Amongst aldehyde & the acid derivatives, acid chloride are the most susceptible to nucleophilic attack due to strong –I effect & weak +R effect of the Cl-atom as a result of which carbonyl carbon has the highest electron deficiency. The actual order is MeCOCl >MeCOOCOMe >MeCOOMe >MeCHO. 14. (ad) 15. (c) Ketone (non-reducing) and aldehyde (reducing) can be distinguished by Fehling solution. 16. (d) 17. (bd) 18. (d) Aldehyde & ketone are colourless & stable compound 19. (c) It undergoes electrophilic substitution at m-position and also gives iodoform test. 20. (a) 21. (b) Due to electron withdrawing nature of group, the partial +ve charge on the carbon atom of the group in p-nitrobenzaldehyde increases and hence becomes more susceptible to nucleophilic attack by ion. 22. (b) Cannizzaro reaction is an example of hydride ion transfer reaction. 23. (d) Except benzophenone react with rest of option. 24. (d) The alcohol can be converted to aldehyde group by treating with oxidising agent Pyridinium chloro chromate it is abbreviated as PCC and is called Collin's reagent. This reagent is used in non aqueous solvent like It is a very good reagent because it checks the further oxidation of aldehyde to carboxylic acid while rest oxidising agent oxidise aldehyde into carboxylic acid. 25. (a) 26. (d) Benzyl alcohol does not have the group or so it will not give the positive iodoform test. 27. (c) This is perkin reaction 28. (b) 29. (c) 30. (a) On complete oxidation the obtained compound shows increament in molecular weight of only 16. It means only one oxygen atom is added here. This condition is fulfilled by only aldehyde which on oxidation gives acid. Hence, original compound must be 31. (a) 32. (d) Acetophenone gives iodoform reaction while benzophenone does give this. 33. (c) 34. (a) The size of the alkyle group. Causes hindrance to attacking group. As the number and size of the alkyl groups incirease the hindrance to the attack of nucleophile also increases. Thus the reactivity follows the order . 35. (b) Benzaldehyde does not have the (-hydrogen so it will undergoes cannizzaro’s reaction. 36. (b) Aldehydes – Those aldehyde in which atom is absent can participate in Cannizzaro’s reaction. 37. (c) 38. (c) 39. (a) Because alkyl group is absent and they have +ve inductive effect and increases the electron density on the carbonyl group. 40. (b) The compound having (-hydrogen will give iodoform test. Ethyl alcohol and secondary alcohols also give positive iodoform test because by the action of halogens in alkaline medium, they are oxidesed to acetaldehyde and methyl ketones respectively. 41. (d) During reaction gets reduced Ag metal and forms silver mirror. 42. (ad) and will give the compounds containing -group. 43. (d) 44. (d) 45. (c) Aldehydes are compounds containing and . So hydrocarbons react with atmospheric oxygen to give aldehydes. 46. (b) Tollen’s reagent is ammonical silver nitrate solution. Its reacting species is . It oxidises aliphatic as well as aromatic aldehydes. 47. (b) This reaction is Friedel–Craft’s acylation. 48. (a) 1-pentanone is an impossible compound does not have group. 49. (a) gives the addition reaction with Aldehyde and only aliphatic ketone. Acetophenone is the aromatic ketone so it does not give the addition product with aldehyde from the addition product with which on treatment with acid or base give again aldehyde. ALDEHYDES & KETONES Mrs. SHALLU JINDAL AGGARWAL : (M): 9878608983 Mrs. SHALLU JINDAL AGGARWAL : (M)9878608983 OH H OH CH3 O O Me Me COOH COOH CHO ⇌ OH OH O CHO COOH COOH CHO CHO CHO CHO (-Hydroxyketone (A) O OH O O D2O OH OH O ... is Q = CH2OH CH2OH O O O O COOH HO HOOC COOH COOH CHO CHO OH O OH O OH OH O HO HO O