In the given conformation is rotated about bond anticlockwise by an angle of 120° then the conformation obtained is [AIIMS 2004]
(a) Fully eclipsed conformation
(b) Partially eclipsed conformation
(c) Gauche conformation
(d) Staggered conformation
The molecular formula of diphenyl methane,
, is
How many structural isomers are possible when one of the hydrogens is replaced by a chlorine atom [CBSE PMT 2004]
(a) 8 (b) 7
(c) 6 (d) 4
reaction is faster in [Orissa JEE 2004]
(a) (b)
(c) (d)
How many enantiomer pairs are obtained by monochlorination of 2, 3-dimethylbutane [Kerala PMT 2004]
(a) Nil (b) Four
(c) Two (d) Three
(e) One
Among the following compounds which can be dehydrated very easily is [AIEEE 2004]
(a)
(b)
(c)
(d)
Which of the following statements is not characteristic of free radical chain reaction [JIPMER 1997]
(a) It gives major product derived from most stable free radical
(b) It is usually sensitive to change in solvent polarity
(c) It proceeds in three main steps like initiation, propagation and termination
(d) It may be initiated by U.V. light
Most stable carbanion is [BHU 2003]
(a) (b)
(c) (d)
Among the following the dissociation constant is highest for
[AIIMS 2004]
(a) (b)
(c) (d)
Which one of the following compounds is most acidic
[CBSE PMT 2005]
(a) (b)
(c) (d)
Which one is electrophilic addition [AMU (Engg.) 1999]
(a)
(b)
(c)
(d)
A compound has 3 chiral carbon atoms. The number of possible optical isomers it can have [DCE 2004]
(a) 3 (b) 2
(c) 8 (d) 4
How many chiral isomers can be drawn from 2-bromo, 3-chloro butane [DCE 2003]
(a) 2 (b) 3
(c) 4 (d) 5
Number of isomers of is
[CBSE PMT 1996; AFMC 1997; RPMT 2002; MP PMT 1997]
(a) 2 (b) 3
(c) 4 (d) Isomerism not exist
The number of possible isomers for compound is [MP PMT 1999]
(a) 2 (b) 3
(c) 4 (d) 5
The optically active tartaric acid is named as D-(+)- tartaric acid because it has a positive [IIT-JEE 1999]
(a) Optical rotation and is derived from D-glucose
(b) pH in organic solvent
(c) Optical rotation and is derived from D(+) glyceraldehyde
(d) Optical rotation only when substituted by deuterium
Among the following compounds (I-III) the correct order of reaction with electrophilic reagent is [CBSE PMT 1997]
(a) II > III > I (b) III < I < II
(c) I > II > III (d) I = II > III
Carbocation which is most stable [BHU 2003]
(a) (b)
(c) (d)
Tautomerism is exhibited by
[CBSE PMT 1997; KCET 2002]
(a) (b)
(c) (d)
Which of the following will have geometrical isomers
[MP PET 1996; MP PMT 1997; AFMC 1997]
(a) 2-methylpropene (b) 2-butene
(c) 1-butene (d) Propene
Examine the following three pairs of possible isomers
Now state whether the pairs represent identical compounds or different isomers
(a) All three pairs represent different compounds
(b) (ia) and (ib) are identical; (iia) and (iib) are identical; and (iiia) and (iiib) are identical
(c) (ia) and (ib) are isomers; (iia) and (iib) are identical; and (iiia) and (iiib) are isomers
(d) (ia) and (ib) are identical; (iia) and (iib) are identical, and (iiia) and (iiib) are isomers
Tautomerism is exhibited by [IIT-JEE 1998]
(a)
(b)
(c)
(d)
The following reaction is described as [CBSE PMT 1997]
(a) (b)
(c) (d)
Which one of the following represents eclipsed form of ethane
(a) (b)
(c) (d) None of these
Which are the staggered forms of ethane
(a) 1 and 4 (b) 3 and 4
(c) 2 and 4 (d) 1 and 3
Which of the following is the most stable cation
[CBSE PMT 1988; MNR 1988; AIIMS 1985]
(a) (b)
(c) (d)
In a reaction of the major product (> 60%) is m-isomer, so the group Y is [AIIMS 1997; UPSEAT 2003]
(a) (b)
(c) (d)
Dehydrohalogenation in presence of is correctly represented by [Orissa JEE 2004]
(a) (b)
(c) (d)
Number of structural isomers of are
[CPMT 1983, 84, 89, 91; MADT Bihar 1984;
MNR 1984; MP PET 1997; Pb. PMT 1999; MH CET 2003]
(a) 3 (b) 6
(c) 7 (d) 10
Among the following the aromatic compound is
[AIIMS 2004]
(a) (b)
(c) (d)
Which of the following compounds are not arranged in order of decreasing reactivity towards electrophilic substitution [DCE 2003]
(a) Fluoro benzene > chloro benzene > bromo benzene
(b) Phenol > n-propyl benzene > benzoic acid
(c) Chloro toluene > para-nitro toluene > 2-chloro-4-nitro toluene
(d) Benzoic acid > phenol > n-propyl benzene
Most stable carbonium ion is [Pb. CET 2004]
(a) (b)
(c) (d)
Which one of the following species is most stable
[IIT-JEE 1995]
(a)
(b)
(c)
(d)
Which of the following gives most stable carbocation by dehydration [RPMT 2002]
(a)
(b)
(c)
(d)
Which of the following orders regarding relative stability of free radicals is correct [UPSEAT 2004]
(a) 3° < 2° < 1° (b) 3° > 2° > 1°
(c) 1° < 2° > 3° (d) 3° > 2° < 1°
The +I effect of alkyl groups is in the order [DCE 2002]
(a) 2° > 3° > 1° (b) 1° > 2° > 3°
(c) 3° > 2° > 1° (d) None of these
Which one has asymmetric C-atom [Roorkee 1995]
(a)
(b)
(c)
(d)
Which of the following compounds will show metamerism
[KCET 1996]
(a) (b)
(c) (d)
How many carbon atoms in the molecule are asymmetric
[MP PET 2001]
(a) 1 (b) 2
(c) 3 (d) None of these
Which of the following act as nucleophiles [Roorkee 1999]
(a) (b)
(c) (d)
Which of the following has the highest nucleophilicity
[IIT-JEE Screening 2000]
(a) (b)
(c) (d)
Keto-enol tautomerism is found in
[IIT-JEE 1988; MADT Bihar 1995]
(a)
(b)
(c)
(d)
Which of the following compounds will show geometrical isomerism [IIT-JEE 1998]
(a) 2-butene (b) Propene
(c) 1-phenylpropene (d) 2-methyl-2-butene
Which behaves both as a nucleophile and electrophile
[IIT-JEE Screening 1991; Pb. CET 1985]
(a) (b)
(c) (d)
The number of optical isomers of an organic compound having n asymmetric carbon atoms will be [MP PET 1994]
(a) (b)
(c) (d)
Total number of isomers of are
[IIT-JEE 1987; DPMT 1983; CPMT 1991;
MNR 1990; MP PET 1995; UPSEAT 2001]
(a) 4 (b) 5
(c) 6 (d) 7
With a change in hybridisation of the carbon bearing the charge, the stability of a carbanion increase in the order
[DCE 2003]
(a) (b)
(c) (d)
The C - C bond length of the following molecules is in the order [IIT-JEE 1991]
(a)
(b)
(c)
(d)
In the reaction a chiral centre is produced. This product would be
[CBSE PMT 1995]
(a) Laevorotatory (b) Meso compound
(c) Dextrorotatory (d) Racemic mixture
Cyclic hydrocarbon molecule ‘A’ has all the carbon and hydrogen in a single plane. All the carbon-carbon bonds are of same length less than 1.54Å, but more than 1.34Å. The bond angle will be [BVP 2003]
(a) (b)
(c) (d)
How many structural isomers are possible for a compound with molecular formula [CBSE PMT 2001]
(a) 2 (b) 5
(c) 7 (d) 9
(c)
2. (d) Only four structural isomers are possible for diphenyl methane.
3. (c) mechanism proceeds through carbocation intermediate.
4. (e)
Due to the presence of chiral carbon it shows the optical activity and its mirror image are non superimposable so it shows one enantiomer pair.
5. (a)
The more stable carbocation is generated thus more easily it will be dehydrated.
6. (b) This option is not characteristics of free radical chain reaction.
7. (c) Due to group in benzene ring,
is most stable carbanion.
8. (d) Dissociation of proton from is very difficult due to –I effect of and while in due to resonance stabilization of phenoxide ion proton eliminate easily similarly due to H-bonding in it can be eliminate and show acidic character by triple bond by which proton can be dissociate.
9. (b)
Electron withdrawing group increases acidic character due to –I and –R effect of hence orthonitrophenol is most acidic.
10. (d) Halogenation on alkene occurs by electrophilic addition.
11. (c) The number of possible optical isomers
(where ‘n’ is the number of chiral c-atoms)
12. (c) 2-bromo, 3-chloro-butane has 2 chiral carbon atoms, hence has optical isomers.
13. (a) ,
14. (b) three isomers are possible
1-bromo-1, 1-dichloroethane
1-bromo-2,2-di-chloroethane
1-bromo-1, 2-dichloroethane
15. (c) D(+)-tartaric acid has positive optical rotation and is derived from D (+) glyceraldehyde.
16. (c) I > II > III
Methoxy group is electron releasing it increases electron density of benzene nucleus while decreases electron density of benzene.
17. (c) Due to resistance benzyl carbonium ion is most stable.
18. (d) ⇌
19. (b)
20. (d) Both 1, 2-dichloro benzene
Hence, identical compounds.
Both, 1, 3-dimethyl benzene
Hence, identical compounds.
(iiia) and (iiib) are position isomers.
21. (a,c,d) (a) ⇌
(c)
(d)
22. (c)
In this reaction inversion of configuration takes place this is called optical inversion. It is an example of reaction (Bimolecular Nucleophillic Substitution).
23. (b) This option shows eclipsed form of ethane.
24. (c) 2nd and 4th forms of ethane are staggered.
25. (b) carbonium ion is most stable.
26. (a)
because it is meta directing group while . and are O and P directing groups.
27. (a)
28. (c) have 7 isomers out of which 4 are alcohols and 3 are ethers.
1. ,
2.
3.
4.
5.
6.
7.
29. (a) According to Huckel rule for aromaticity the molecule must be planar, cyclic system having delocalised (4n + 2)( electron where n is an integer equal to 0, 1, 2, 3, thus the aromatic comp. have delocalised electron cloud of
2, 6, 10 or 14( electron cyclopropenyl cation have the 2( electron (n = 0) so it is aromatic.
30. (d) –COOH group is a deactivating group, hence benzoic acid is less reactive towards electrophilic substitution than phenol.
31. (c) In the triphenyl methyl carbonium ion the ( electrons of all the three benzene rings are delocalised with the vacant p-orbital of central carbon atom. So, it is resonance stabilised. It is the most stable of all the carbonium ions given
The ion is stabilised by hyperconjugation, a second order resonance.
32. (b)
Nitro-group is electron withdrawing therefore decreases stability.
Methoxy group is electron releasing.
Therefore increases stability by donating electron.
Chlorine is also electron withdrawing but its effect is less than group.
Hence, correct order of stability.
33. (b) 3° alcohols is most stable carbocation
34. (b) Due to the increasing no. of hyperconjugative structures free radical stabilise following as .
35. (c)
36. (b,c) and
37. (b) and
are metamers.
38. (b)
Two carbon atoms in the molecule are asymmetric.
39. (a,b,d) are nucleophiles due to presence of lone pairs.
40. (c) has the highest nucleophilicity.
41. (c,d)
and
42. (a,c) 2-butene
and
and
43. (c) behaves both as nucleophile and electrophile.
44. (c) , n = no. of asymmetric carbon atoms.
45. (b) 1.
2.
3.
4.
5.
46. (c) Stability of carbanions increase with increase in s-character of hybrid orbitals of carbon bearing charge, hence correct order is : .
47. (b)
48. (d)
(Both d and l forms are obtained) Hence, product will be a racemic mixture.
49. (d) Molecule ‘A’ is benzene because in benzene bond length is between single and double bond.
50. (a) Two isomers and
are possible for .
GENERAL ORGANIC CHEMISTRY
Mrs. SHALLU JINDAL AGGARWAL : (M)9878608983
CH3
CH3
Cl
Cl
Cl
Cl
O
OH
NO2
CH2–
NO2
provides stable carbocation intermediate because it has tertiary carbon.
(iii)
Cl
CH2
(iv)
Cl
|
CH
(ii)
Cl
CH2
(i)
Cl
CH2
+
+
(
OH
H
Br
(
OH
H
Br
OH–
H
Br
OH–
H
Br
4
H
H
H
H
H
H
C
H
H
H
3
C
H
H
H
1
H
H
H
H
H
H
2
C
H
H
H
C
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
O
O
O
O
O
O
CH = CH – OH
H3C
(iib)
CH3
Cl
(ib)
Cl
(iiib)
COOH
COOH
HOOC
(iiia)
COOH
(ia)
Cl
Cl
(iia)
CH3
CH3
III
NO2
II
I
OCH3
OH
CH3
OH
NO2
OH
CH2
C4
C2
C1
C3
H
H
H
CH3
CH3
H
COOH
HOOC
COOH
O
⇌
O
⇌
O
O
O
Br
H
OH–
+
CH3
C4
C2
C1
C3
H
H
H
H3C
H
60°
Gauche conformation
C4
C2
C1
C3
H
H3C
H
CH3
H
H
60°
C4
C2
C1
C3
H
H
H
CH3
CH3
H