JEE Main Previous Year Papers Questions With Solutions Chemistry General Organic Chemistry

JEE Main Previous Year Papers Questions With Solutions Chemistry  General Organic Chemistry

1.Arrangement of (CH₃)₃– C-, (CH₃)-CH-, CH₃– CH₂-, when attached to benzyl or an unsaturated group, in increasing order of inductive effect is (2002)
1)(CH₃)₃-C – < (CH₃)₂ – CH – < CH₃ – CH₂
2)CH₃-CH₂ – < (CH₃)₂ – < CH – < (CH₃)₃-C –
3)(CH₃)₂ – CH < (CH₃)₃ – C -< CH₃ – CH₂
4)(CH₃)₃ – C -< CH₃ – CH2 < (CH₃)₂ – < CH
Ans.(2) -CH₃ group has + I effect, as number of -CH₃ group increases, the inductive effect increases.

2.Which of the following does not show geometrical isomerism ? (2002)
1)1, 2 – dichloro – 1 – pentane
2)1,3- dichloro – 2 – pentane
3)1,2- dichloro – 1 – pentane
4)1, 4 – dichloro – 2 – pentane
Ans.

3.A similarity between optical and geometrical isomerism is that           (2002)
1)each forms equal number of isomers for a given compound
2)If in a compound one is present then so is the other
3)both are included in stereoisomerism
4)they have no similarity
Ans.(3) Optical and geometrical isomers are stereoisomers.

4.Which of the following compounds has wrong IUPAC name ?           (2002)

Ans.(3) Correct name is 3-methyl – 2-butanol.

5. Racemic mixture is formed by mixing two
1)isomeric compounds (2002)
2)chiral compounds
3)meso compounds
4)optical isomers
Ans.(4) Racemic mixture is formed when enantiomers are mixed in equimolar proportion.

6.The IUPAC name of CH₃COCH(CH₃)₂ is
1)2-methyl-3-butanone (2003)
2)4-methylisopropyl ketone
3)3-methyl-2-butanone
4)Isopropylmethyl ketone
Ans.

7.3The general formula C_nH_2n0₂ could be for open chain (2003)
1) carboxylic acids       2) diols
3) dialdehydes              4) diketones
Ans.(1) Carboxylic acid or ester.

8.Among the following four structures I to IV.it is true that  (2003)

1)only I and II are chiral compounds
2)only III is a chiral compound
3)only II and IV are chiral compounds
4)all four are chiral compounds
Ans.(1) A chiral object or structure has four different groups attached to the carbocation.

9.The compound formed in the positive test for nitrogen with the Lassaigne solution of an organic compound is  (2004)
1) Fe₄[Fe(CN)₆]₃           2) Na₄[Fe(CN)₅NOS]
3) Fe(CN)₃                    4) Na₃[Fe(CN)₆]
Ans.(1) Prussian blue coloured complex compound is ferric ferrocyanide.

10.The IUPAC name of the compound (2004)

1)3,3- dimethyl -1- hydroxycyclohexane
2)1,1 – dimethyl -3- cyclohexanol
3)3,3- dimethyl -1- cyclohexanol
4)1,1 – dimethyl -3- hydroxycyclohexane
Ans. (2)Methyl groups are at position 3.

11.Which one the following does not have sp² hybridized carbon ?  (2004)
1)Acetone                                2) Acetamide
3) Acetonitrile                       4) Acetic acid
Ans.(3) It is having only sp³ and sp hybridized carbon atom.

12.Which of the following will have meso-isomer also ? (2004)\
1)2- chlorobutane
2)2- hydroxyopanoic acid
3)2,3- dichloropentane
4)2-3- dichlorobutane
Ans.

13. Amongst the following compound, the optically active alkane having lowest [ molecular mass is       (2004)

Ans.

14.Which of the following compound is not chiral?  (2004)
1)1-chloropentane’
2)3-chloro-2-methyl pentane
3)1-chloro -2-methyl pentane
4)2-chloropentane
Ans.

15.Due to the presence of an unpaired electron, free radicals are (2005)
1)Chemically reactive   2) Chemically inactive   3) Anions 4) Cations
Ans.(1) Free redicals are chemically active.

16.The decreasing order of nucleophilicity among the nucleophiles         (2005)

Ans.(4) Highest n cloud is present in CN-

17.Of the five isomeric hexanes, the isomer which can give two monochlorinated compounds is (2005)
1)n-hexane     2)    2, 3-dimethylbutane
3) 2,2-dimethylbutane    4)   2-methylpentane
Ans.

18.Which types of isomerism is shown by 2,3-dichlorobutane ?   (2005)
1)Diastereo         2)    Optical
3) Geometric     4)    Structural
Ans.

Ans.(3) Double bond is given higher preference

20.The increasing order of stability of the following free radicals is   (2006)

Ans.(1) Triphenyl free radical is most stable.

21.Increasing order of stability among the three main conformations (i.e. Eclipse, Anti, Gauche) of 2-fluoroethanol is    (2006)
1)Eclipse, Gauche, Anti
2)Gauche, Eclipse, Anti
3)Eclipse, Anti, Gauche
4)Anti, Gauche, Eclipse
Ans.(3) Eclipse is least stable and gauche is most stable.

22.Which of the following molecules is expected to rotate the plane of plane polarized light? (2007)

Ans.(1) The plane of polarized light is rotated by optically active compound. Compound should be chiral.So, option (1) has, chiral C-atom. So, it is optically active.In (2), (3) and (4) plane of symmetry is present.

23.Which one of the following conformation of cyclohexane is chiral ? (2007)
1) Twist boat               2) Rigid
3) Chair                        4) Boat
Ans.(1) Twisted boat is chiral as it does not have plane of symmetry.

Ans.

Ans.

26.The correct decreasing order of priority for the functional groups of organic compounds in the IUPAC system of nomenclature is(2008)
1)- COOH, – S0₃H, – CONH₂, – CHO
2)- SO3H, – COOH, – CONH2, – CHO
3)- CHO, – COOH, – S0₃H, – CONH,
4)- CONH₂, – CHO, – S0₃H, – COOH
Ans. (2) – S0₃H, – COOH, – CONH₂, – CHO

Ans.(3) 2° carbanion js more stable than 3°. Chlorine causes-I effect

28.The alkene that exhibits geometrical isomerism is      (2009)
1) propene                             2) 2-methyl propene
3) 2-butene                            4) 2-methyl -2-butene
Ans.

29.The number of stereoisomers possible for a compound of the molecular formula CH₃ – CH = CH – CH(OH) – Me is (2009)
1) 3                   2) 2             3) 4           4) 6
Ans.(3) About the double bond, two geometrical v isomers are possible and the compound is m having one chiral carbon.

30.The IUPAC name of  neopentane is (2009)
1) 2-methylbutane  2) 2, 2-dimethylpropane  3) 2-methylpropane  4) 2, 2-dimethylbutane
Ans.

31.5 mg of an organic compound containing nitrogen was digested according to Kjeldahl’s method and the evolved ammonia was absorbed in 20 mL of 0.1 M HC1 solution. The excess of the acid required 15mL of 0.1 M NaOH solution for complete neutralization. The percentage of nitrogen in the compound is (2010)
1) 59.0       2) 47.4        3) 23.7        4) 29.5
Ans.

32.Out of the following, the alkene that exhibits optical isomerism is (2010)
1)3 – methyl- 2 – pentane
2)4 – methyl – 1- pentane
3)3 – methyl – 1 – pentane
4)2 – methyl – 2 – pentane
Ans.

33.Identify the compound that exhibits tautomerism (2011)
1) 2 – Pentanone  2) Phenol  3) 2 – Butene            4) Lactic acid
Ans.

34.How many chiral compounds are possible on monocblorination of 2-methylbutane ? (2012)
1) 8      2) 2      3) 4      4) 6
Ans.

35.A solution of (-1) – 1 – 1 – chloro-1- phenylethane in toluene racemises slowly in the presence of a small amount of SbCl₅, due to the formation of    (2013)
1) carbanion                  2) carbene
3) carbocation               4) free radical
Ans.

Ans.(4) Primary carbocation is less stable.

37.For the estimation of nitrogen, 1.4 g of an organic compound was digested by Kjeldahl method and the evolved ammonia was M /10 absorbed in 60mL of M/10 sulphuric acid. The unreacted acid required 20 mL of — sodium hydroxide for complete neutralization. The percentage of nitrogen in the compound is(2014)
1) 5 %        2) 6%         3) 10%        4) 3%
Ans.

Ans.

Ans.

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