JEE Main Previous year questions (2016-20): Aldehydes, Ketones & Carboxylic Acids Notes | EduRev

Chemistry 35 Years JEE Main & Advanced Past year Papers

JEE : JEE Main Previous year questions (2016-20): Aldehydes, Ketones & Carboxylic Acids Notes | EduRev

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Q.1. What is the product of following reaction?    (2020)

(1)
(2)
(3)
(4)
Ans.
(4)
The reaction involved is


Q.2. The predominant intermolecular forces present in ethyl acetate, a liquid, are    (2020)
(1) London dispersion and dipole-dipole
(2) Hydrogen bonding and London dispersion
(3) Dipole-dipole and hydrogen bonding
(4) London dispersion, dipole-dipole and hydrogen bonding
Ans.
(1)
There are two type of forces exist in ethyl acetate a liquid. First is London dispersion forces between the hydrocarbon part of the molecule and second is dipole-dipole interaction between carbonyl carbon and oxygen of one molecule with another molecule.


Q.3. The most suitable reagent for the given conversion is    (2020)

(1) B2H6
(2) NaBH4
(3) LiAlH4
(4) H2/Pd
Ans.
(1)
The reaction involved is


Q.4. The major product in the following reaction is    (2020)

(1)
(2)
(3)
(4)
Ans.
(4)
The reaction involved is


Q.5. An unsaturated hydrocarbon X absorbs two hydrogen molecules on catalytic hydrogenation, and also gives following reaction

X will be    (2020)
(1)
(2)
(3)
(4)
Ans.
(3)
By back tracking the reaction, the aldehyde which on reaction with Tollens’ reagent gives 3-oxohexanedicarboxylic acid is

Above product is obtained by the ozonolysis of compound given in option (3), that is,

The above compound can above two molecules of hydrogen to give cycloalkane.
Thus, the reaction involved is


Q.6. Identify (A) in the following reaction sequence:    (2020)

(1)
(2)
(3)
(4)
Ans.
(2)
Solution.
The reaction involved is


Q.7. Consider the following reactions    (2020)

The mass percentage of carbon in A is________.
Ans.
(66.67)
The reaction involved is

The molecular formula of A is C4H8O.
The molar mass of A = 72.0 g mL–1
Mass percentage of C


Q.8. The major product of following reaction is:    (2019)

(1) RCOOH
(2) RCONH2
(3) RCHO
(4) RCH2NH2
Ans.
(3)

The reduction of nitriles to aldehydes can be done using DIBAL-H.

Q.9. The major product formed in the following reaction is:    (2019)

(1)
(2)
(3)
(4)
Ans.
(3)



Q.10. The tests performed on compound X and their inferences are:

Compound ‘X’ is:    (2019)
(1)
(2)
(3)
(4)
Ans.
(2)
2, 4 DNP test is given by aldehydes and ketones
lodoform test is given by

Azo dye test not given by


Q.11.
(1)
(2)
(3)
(4)
Ans.
(4)
NaBH4 is a selective reducing agent, used for the reduction of aldehydes and ketones, it does not affect alkene and ester.


Q.12. The major product of the following reaction is:    (2019)

(1)
(2)
(3)
(4)
Ans.
(4)
Reaction involved:


Q.13. The major product obtained in the following reaction is:    (2019)

(1)
(2)
(3)
(4)
Ans. 
(4)
Reaction involved:


Q.14. The major product of the following reaction is:    (2019)

(1)
(2)
(3)
(4)
Ans.
(4)


Q.15. The major product of the following reaction is:    (2019)

(1)
(2)
(3)
(4)
Ans. 
(3)


Q.16. The major product of the following reaction is:    (2019)

(1)
(2)
(3)
(4)
Ans.
(3)
DIBAL-H will reduce cyanides and esters to aldehydes.


Q.17.  cannot be prepared by:    (2019)
(1) CH3CH2COCH+ PhMgX
(2) PhCOCH2CH3 + CH3MgX
(3) PhCOCH3 + CH3CH2MgX
(4) HCHO+PhCH(CH3)CH2MgX
Ans. 
(4)
Tertiary alcohol is prepared by the reaction of Grignard reagent with a ketone (formaldehyde is used to prepare primary alcohol).


Q.18. In the following reaction    (2019)

The best combination is:
(1) CH3CHO and tBuOH
(2) HCHO and MeOH
(3) CH3CHO and MeOH
(4) HCHO and tBuOH
Ans.
(2)
Best combination is HCHO (more reactive aldehyde) and MeOH (less stericallv hindered alcohol).


Q.19. In the following reactions, products A and B are:    (2019)

(1)
(2)
(3)
(4)
Ans.
(1)



Q.20. The major product of the following reaction is:    (2019)

(1)
(2)
(3)
(4)
Ans. 
(2)

NaBH4 does not reduce the double bond but can reduce keto group

Q.21. The aldehydes which will not form Grignard product with one equivalent Grignard reagents are:    (2019)
(1)
(2)
(3)
(4)
(1) (B), (D)
(2) (B), (C)
(3) (B), (C), (D)
(4) (C), (D)
Ans. 
(1)
Grignard reagent will not react with aldehydes if it has a functional group which contains acidic hydrogen. Thus options (B) and (D) have—COOH and—CH2OH respectively which contain acidic H-atom. Therefore, acid-base reaction occurs.



Q.22. An organic compound neither reacts with neutral ferric chloride solution nor with Fehling solution. It however, reacts with Grignard reagent and gives positive iodoform test. The compound is:    (2019)
(1)
(2)
(3)
(4)
Ans.
(4)



Q.23. The major product of the following reaction is:    (2019)

(1)
(2)
(3)
(4)
Ans.
(4)


Q.24. The major product obtained in the following reaction is:    (2019)

(1)
(2)
(3)
(4)
Ans. 
(2)


Q.25. In the following reaction
Carbonyl compound +
Rate of the reaction is the highest for:    (2019)
(1) Acetone as substrate and methanol in excess.
(2) Propanal as substrate and methanol in stoichiometric amount.
(3) Propanal as substrate and methanol in excess.
(4) Acetone as substrate and methanol in stoichiometric amount.
Ans.
(3)

Generally, aldehydes are more reactive than ketones in nucleophilic addition reactions.
∴ Rate of reaction with alcohol to form acetal and ketal is


Q.26. Major products of the following reaction are:    (2019)

(1)
(2)
(3)
(4) CH3OH and HCO2H
Ans. 
(3)

 




Q.27. Compound A(C9H10O) shows positive iodoform test. Oxidation of A with MnO4/KOH gives acid B(C8H6O4). Anhydride of B is used for the preparation of phenolphthalein. Compound A is:    (2019)
(1)
(2)
(3)
(4)
Ans. 
(4)
 

Q.28. Which dicarboxylic acid in presence of a dehydrating agent is least reactive to give an anhydride?    (2019)
(1)
(2)
(3)
(4)
Ans.
(1)

Adipic acid does not form anhydride.

Q.29. The decreasing order of ease of alkaline hydrolysis for the following esters is    (2019)
 



(1) III > II > IV > I
(2) III > II > I > IV
(3) IV > II > III > I
(4) II > III > I > IV
Ans.
(2)
Rate of reaction ∝ Electrophilicity of carbonyl carbon, so, E.W.G. increases rate while E.R.G. decreases the rate.



Q.30. The major product of the following reaction is:    (2019)
CH3CH = CHCO2CH3 
(1) CH3CH2CH2CO2CH3
(2) CH3CH = CHCH2OH
(3) CH3CH2CH2CH2OH
(4) CH3CH2CH2CHO
Ans.
(2)
LiAlH4 reduces esters to alcohols but does not reduce C = C.


Q.31. The major product of the following reaction is:    (2019)

(1)
(2)
(3)
(4)
Ans.
(1)

Acid catalysed intramolecular esterification reaction.


Q.32. The major product of the following reaction is:    (2019)

(1)
(2)
(3)
(4)
Ans.
(2)


Q.33. The major product ‘Y’ in the following reaction is:    (2019)

(1)
(2)
(3)
(4)
Ans. 
(1)


Q.34. The major product of the following reaction is:    (2019)

(1)
(2)
(3)
(4)
Ans.
(2)
 

Q.35. The main reduction product of the following compound with NaBH4 in methanol is:    (2018)

(1)
(2)
(3)
(4)
Ans.
(1)
Sodium borohydride will reduce ketone to alcohol. It will not reduce amide group and C = C double bond.
Hence, option (1) is the correct answer.

Q.36. The reagent(s) required for the following conversion are:    (2018)

(1) (i)LiAlH4 (ii) H3 O+ 
(2) (i) B2 H6 (ii) SnCl2/HCl  (iii) H3O+ 
(3) (i)B2H6  (ii)DIBAL-H (iii)H3O+ 
(4) (i)NaBH4 (ii)Raney Ni/H2 (iii)H3O+ 
Ans.
(3)


Q.37. The major product B formed in the following reaction sequence is:   (2018)

(1)
(2)
(3)
(4)
Ans.
(4)


Q.38. The correct sequence of reagents for the following conversion will be    (2017)

(1) [Ag(NH3)2]+OH-, H+/CH3OH, CH3MgBr 
(2) CH3MgBr, H+/CH3OH, [Ag(NH3)2]+OH- 
(3) CH3MgBr, [Ag(NH3)2]+OH-, H+/CH3OH 
(4) [Ag(NH3)2]+OH-, CH3MgBr, H+/CH3OH 
Ans.
(1)



Q.39. The major product obtained in the following reaction is    (2017)

(1)
(2)
(3)
(4)
Ans. (2) 
DIBAL — H reduces esters and carboxylic acids into aldehydes 


Q.40. A compound of molecular formula C8H8O2 reacts with acetophenone to form a single cross-aldol product in the presence of base. The same compound on reaction with conc. NaOH forms bezyl alcohol as one of the products. The structure of the compound is:    (2017)
(1)
(2)
(3)
(4)
Ans.
(1)
 


Q.41. The reaction of propene with HOCl (Cl2 + H2O) proceeds through the intermediate:    (2016) 
(1) CH3 - CH+ - CH2 - OH 
(2) CH3 - CH+ - CH2 - Cl 
(3) CH3 - CH(OH) - CH+2 
(4) CH3 - CHCl - CH+2 
Ans.
(2)


Q.42. The correct statement about the synthesis of erythritol (C(CH2OH)4) used in the preparation of PETN is:    (2016)
(1) The synthesis requires two aldol condensations and two Cannizzaro reactions.
(2) Alpha hydrogens of ethanol and methanol are involved in this reaction.
(3) The synthesis requires four aldol condensations between methanol and ethanol.
(4) The synthesis requires three aldol condensations and one Cannizzaro reaction.
Ans.
(4)
The synthesis requires three aldol & one cannizzaro reaction.


Q.43. Consider the reaction sequence below:    (2016)

(1)
(2)
(3)
(4)
Ans.
(4)
 

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