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Dr. Sangeeta Khanna Ph.D 1 CHEMISTRY COACHING CIRCLE D:\Important Data\2016\+2\Org\Test\Grand Test\+2 Grand Test-5\+2 Grand Test-V.doc
Isomerism
Organic Halide
Dr. Sangeeta Khanna Ph.D
Dr. Sangeeta Khanna Ph.D 2 CHEMISTRY COACHING CIRCLE D:\Important Data\2016\+2\Org\Test\Grand Test\+2 Grand Test-5\+2 Grand Test-V.doc
Test Date: 20.8.2016 Topic: Organic Halide & Isomerism
READ INSTRUCTIONS CAREFULLY 1. The test is of 2 hour duration. 2. The maximum marks are 380. 3. This test consists of 87 questions. 4. Keep your mobiles switched off during Test in the Halls.
(Single Correct Choice Type) Negative Marking [-1]
This Section contains 45 multiple choice questions. Each question has four choices A), B), C) and D) out
of which ONLY ONE is correct. Marks: 45 × 4 = 180
1. In the given reaction PhMgBr + D2O (X); (X) will be:
a. b. c. d.
D
Sol.
2. When the concentration of alkyl halide is triple and concentration of HOΘ
is reduced to half, the rate of
SN2
a. 3 times b. 1.5 times c. 2 times d. 6 times
B
Sol. Rate = K[Halide] [OH–]
3.
Compound A is:
a. b. c. d.
A Sol. [Diazotisation & sandmeyer] 4. Order of stability of alkene is
)X(23 CHCHCH
)Y(
2
3
3
CHCCH
CH
\/
)Z(
2
3
3
|
|3 CHCH
CH
CH
CCH is:
a. X > Y > Z b. Y > X > Z c. Z > X > Y d. Y > Z > X B
Sol. [Stability Hyperconjugation]
OH OD D
MgBr D DOD
Br
Br
NH2 NH2
Br
N2Br
NH2 1. NaNO2 + HCl
2. HBr, CuBr A
Dr. Sangeeta Khanna Ph.D
Dr. Sangeeta Khanna Ph.D 3 CHEMISTRY COACHING CIRCLE D:\Important Data\2016\+2\Org\Test\Grand Test\+2 Grand Test-5\+2 Grand Test-V.doc
5. Geometrical isomerism is possible in :
a. b. c. d. D
6. a. Diastereomers b. Enantiomers c. Tautomers d. Conformers A 7. Which of the following is used as a purity test for chloroform?
a. aq. KOH b. aq. KOH + AgNO3 c. AgNO3 solution d. Oxidation test C
8. t-butyl bromide temp. low
KOH .aq (X). The main product (X) is
a. tertiary butyl alcohol b. 1-butoxy butane c. iso-butylene d. propene A
9. When ethyl benzene is treated with one equivalent N-bromosuccinimide in CCl4, the major product obtained is
a. b. c. d. B Sol. Benzylic Bromination with NBS 10. The decreasing reactivity order of halides towards dehydrohalogenation is
a. RI > RCl > RBr > RF b. RI > RBr > RCl > RF c. RF > RCl > RBr > RI d. RF > RI > RBr > RCl B
11. C6H5 – CH3 + Cl2 K 800
C6H5CH2Cl + HCl. This reaction takes place mainly by
a. SN1 mechanism b. SN2 mechanism c. free radical mechanism d. E1 mechanism C
12. (A) 3 AgNO)ii(
NaOH aq.)i( white precipitate.
(A) can be a. vinyl chloride b. benzyl chloride c. chlorobenzene d. o-chlorotoluene B
OH
OH
H
OH
H
H
HO
H
H
O
CH2OH
and
OH
H
OH
H
H
HO
H
H
O
CH2OH
HO
are:
CH2CH2Br CH(Br)CH3 CH2CH3
Br
CH2CH3
Br
Dr. Sangeeta Khanna Ph.D
Dr. Sangeeta Khanna Ph.D 4 CHEMISTRY COACHING CIRCLE D:\Important Data\2016\+2\Org\Test\Grand Test\+2 Grand Test-5\+2 Grand Test-V.doc
13. In an SN1 reaction on chiral centres, there is:
a. inversion more than retention leading to partial racemization b. 100% retention c. 100% inversion d. 100% racemization A
Sol. SN1 reaction gives racemic mixture with slight predominance of that isomer which corresponds to inversion because SN1 also depends upon the degree of 'shielding' of the front side of the reacting carbon.
14. is (B) product The )B()A(ICHCHH
CH
CClH/OH
mole 1
CN22
|
2Θ
3
a. HOOC – CH2 – CH2 – I b. COOHCHCHH
CH
CHOOC 22|
3
c. COOHCHCHH
CH
CCl 22|
3
d. ICHCHH
CH
CHOOC 22|
3
C Sol. Iodide is more reactive & -CN gp on complete hydrolysis give acid. 15. What will be the order of reactivity for the nucleophilic substitution of chlorine in the following compounds? a. (A) > (C) > (B) > (D) b. (D) > (B) > (A) > (C) c. (C) > (A) > (B) > (D) d. (D) > (B) > (C) > (A) B Sol. [e– withdrawing gp increases Reactivity]
16. Which of the following alcohols will give a yellow coloured precipitate with iodine and sodium hydroxide?
a. b. c. d. D 17. The correct order of SN2 reactivity among the following is
a. CH3Cl > CH3Br > CH3I b. CH3Br > CH3CH2Br > (CH3)2CHBr c. CH3CH2Cl > CH3CH2CH2Cl > CH3Cl d. (CH3)3CBr > (CH3)2CHBr > CH3CH2CH2Br B
Cl
NO2
Cl
NO2
Cl
OH
Cl
CHO
NO2
(A) (B) (C) (D)
CH2 C CH
CH3
CH3
CH3
OH CH2 CH2 CH2 C CH3
CH3
OH
OH
CH3
CH2 CH CH3
OH CH3
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Dr. Sangeeta Khanna Ph.D 5 CHEMISTRY COACHING CIRCLE D:\Important Data\2016\+2\Org\Test\Grand Test\+2 Grand Test-5\+2 Grand Test-V.doc
18. Which of the following is the correct order of dipole moment of methyl halides?
a. CH3F > CH3Cl > CH3Br > CH3I b. CH3Cl > CH3F > CH3Br > CH3I c. CH3I > CH3Br > CH3F > CH3Cl d. CH3I > CH3Br > CH3Cl > CH3F B
19. 2-Bromopentane 3 3 3 3(CH ) COK /(CH ) COH
P
The major product (P) formed in the above reaction is a. pent-1-ene b. cis pent-2-ene
c. trans pent-2-ene d. 33|
223 )CH(OCH
CH
CCHCHCH
3
A Sol. Hoffmann’s product with Bulky base. 20. Chloroform on boiling with NaOH solution gives
a. sodium methoxide b. Methanal c. sodium methanoate d. dichloromethanol C
Sol. 3KOH KOH3CHCl HCOOH HCOOK
21. The organic compound formed in the following reaction is
C6H5COOAg + Br2 ref lux/CCl4 product
a. C6H5COOBr b. C6H5Br c. d.
B
22. The product formed when isopropyl alcohol is heated with a Cl2 + NaOH(aq.) is
a. propyne b. 2-chloropropane c. chloroform d. carbon tetrachloride C
23. The correct order of reactivity of the following alcohols with hydrobromic acid (HBr) is
)I(
ol1anphenylprop1 )II(
ol2anphenylprop1 )III(
ol1anphenylprop3
a. I > II > III b. I > III > II c. III > I > II d. III > II > I A
Sol. Order of Reactivity Pri. < Sec. < tert. 24. Which of the following statements is correct?
a. CH3CH2S– is a stronger base, but weaker nucleophile than CH3CH2O
–. b. CH3CH2S
– is a weak base, but more nucleophilic than CH3CH2O–.
c. CH3CH2S– is a stronger base and more nucleophile than CH3CH2O
–. d. CH3CH2S
– is a weak base and less nucleophilic than CH3CH2O–.
B 25. Identify the false statement among the following
a. The rate of hydrolysis of tert-butyl chloride does not change by increasing the concentration of OH–
[SN1]
b. 2-phenylethanol reacts with thionyl chloride to give a chloro compound with almost complete retention of configuration [SNi]
c. Polar solvents generally increase the rate of SN1 reactions. d. SN2 reaction of optically active substrate leads to racemization if the leaving group is attached to
the chiral carbon. D
COOBr
Br
COOH
Br
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Dr. Sangeeta Khanna Ph.D 6 CHEMISTRY COACHING CIRCLE D:\Important Data\2016\+2\Org\Test\Grand Test\+2 Grand Test-5\+2 Grand Test-V.doc
26. The configuration of the product in the following reaction a. b. c. d. None B 27. What is the relationship between the pair of compounds shown? a. Identical: superimposable without bond rotations b. Conformations
c. Stereoisomers d. Constitutional isomers C
28. Correct IUPAC name of following compound is
a. 2-Chlorocyclohexene b. 3-Chlorocyclohexene c. Cyclohexenylchloride d. 1-Chlorocyclohex-2-ene B
29. is X ;X2Cl Fe
a. b. c. d. None
B Sol. CCl3 group is meta directing. 30. Which of the following reaction(s) can be used for the preparation of alkyl halides ?
(I) 2anh. ZnCl3 2CH CH OH HCl
(II) CH3CH2OH + HCl
(III) (CH3)3COH + HCl (IV) 2anh. ZnCl3 2(CH ) CHOH HCl
a. (I) and (II) only b. (IV) only c. (III) and (IV) only d. (I), (III) and (IV) only D Sol. (I) and (IV) can be used due to presence of anhydrous ZnCl2 (III) gives alkyl halide due to formation of
more stable carbocation.
D
Br H
CH2 – CH3
NaI/acetone Product
D
H
CH2 – CH3
I
D
H
CH2 – CH3
I
CH2 – CH3
D
I H
H
H3C
H H
H3C
H
Cl
CCl3
Cl
CCl3
Cl
CCl3
Cl
CCl3
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Dr. Sangeeta Khanna Ph.D 7 CHEMISTRY COACHING CIRCLE D:\Important Data\2016\+2\Org\Test\Grand Test\+2 Grand Test-5\+2 Grand Test-V.doc
31. Which of the following statements is not correct for a nucleophile ?
a. Ammonia is a nucleophile b. Nucleophiles attack low e– density sites
c. Nucleophiles are not electron seeking d. Nucleophile is a Lewis acid
D
Sol. Reason: Nucleophiles are electron rich species so act as Lewis base.
32. The number of structural isomers possible from the molecular formula C3H9N is :
a. 5 b. 2 c. 3 d. 4
D
Sol.
33. In the reaction with HCl, an alkene reacts in accordance with the Markovnikov's rule, to give a product
1-chloro-1-methylcyclohexane. The possible alkene is
a. b. c. d.
A,D
Sol. 34. a. b. c. d. No reaction D Sol. H and Br are not anti position.
CH2 CH3 CH3 CH = CH2
CH2
H+
CH3
Cl–
Cl
CH3 CH3
Cl–
Cl
CH3 or
CH3
Br
CH3ONa Product:
CH3
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Dr. Sangeeta Khanna Ph.D 8 CHEMISTRY COACHING CIRCLE D:\Important Data\2016\+2\Org\Test\Grand Test\+2 Grand Test-5\+2 Grand Test-V.doc
35. Which Bromine is most reactive for SN2 attack of CH3O
– ion a. I b. II c. III d. IV A
Sol. [electron withdrawing group increases Reactivity in SN2]
36. a. b. c. d.
B
37. 2 4
3
Cl (1 mol) NBS / CCl6 5 3
FeClC H CH (A) (B)
The structure of (c) is
a. b. c. d.
A
Sol.
Br
Br
Br
Br
O
(I)
(IV)
(II)
(III)
Br
Br
Br
Br
O
(I)
(IV)
(II)
(III)
HO CH = CH – CH3 HBr Major product:
CH2 – CH – CH3
Br
HO
Br
CH – CH2 – CH3 HO
CH = CH – CH2 – Br HO CH2 – CH2 – CH2 – Br HO
CH2CH2CH2OH
Cl
CH2CH2CH2OH
CH3
Cl
CH CH2
O
Cl
CH2CH2OH
(i) Mg/ether
(ii)
O
(iii) H3O+
(C)
CH3
Cl
NBS
CH2Br
Cl
Mg
CH2MgBr
O
CH2 – CH2 – CH2
OH
Cl
(i)
(ii) HOH Cl
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Dr. Sangeeta Khanna Ph.D 9 CHEMISTRY COACHING CIRCLE D:\Important Data\2016\+2\Org\Test\Grand Test\+2 Grand Test-5\+2 Grand Test-V.doc
38. To prepare 2-Methylbutane from ethyl chloride which of following will be the best reagent?
a.
3
3|
CH CH Cl Na (dryether)
CH
b.
3
3|
CH CH Li CuX
CH
c. CH3CH2CH2 – Li + CuX d.
3| Na
3 2
CH
CH C CH Cl (dryether)H
B Sol. 39. Which of the following alkyl bromides may be used for the synthesis of 2, 3-dimethyl butane by Wurtz
reaction?
a. b. c. Isobutyl bromide d. s-butyl bromide B
Sol. 40. Which among the following pairs are diastereomers:
1. 2. 3. 4. Select the correct answer from the codes given below : a. only 2 b. only 1 c. 1 and 2 d. 1, 2 and 4 D 41. Which of the following compounds are meso forms?
a. 1 only b. 3 only c. 1 and 2 d. 2 and 3
B
CH3 CH Cu LI
CH3
+ CH3CH2 Cl
2CH3 CH Li
CH3
CH3 CH CH2 CH3
CH3
2-Methylbutane
CuX
2
Br
Br
Br + 2Na + Br dry ether
CH3
H
C C
H
CH3
and
CH3
H
C C
H
CH3
COOH
CH2OH
C
C H
H
OH
OH
COOH
CH2OH
C
C H
H
HO
OH
and
CH2OH
C OH
CHO
H and
CH2OH
C
CHO
H HO
Br
C
C C
F
I
Br
C
C C
F
I and
OH H
C2H5
H OH
CH3
1
H
H
CH3
2
Cl
Cl
CH3
CH3
CH3
3
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Dr. Sangeeta Khanna Ph.D 10 CHEMISTRY COACHING CIRCLE D:\Important Data\2016\+2\Org\Test\Grand Test\+2 Grand Test-5\+2 Grand Test-V.doc
42. Consider the following pair of compounds: Which among the following statements is correct?
1. Both are enantiomers 2. Both are in threo form 3. Both are diastereomers 4. Both are in erythro form
a. 1 and 2 b. 1, 2 and 3 c. 2 and 3 d. 3 and 4 A
43. Consider the following reaction sequence In this B and D respectively are a. b. c. d. A 44. A hydrocarbon ‘A’ with molecular mass 84 gives a single monochloride but four dichlorides (only
structural) on photochemical chlorination. The hydrocarbon ‘A’ is
a. Cyclopentane b. Cyclohexane c. 2, 3-Dimethylbutane d. Methyl cyclopentane B
Sol.
Single monochloro product
Four dichloro products 45. Match the column – I with column – II
Column I Column II
(A) Chlorobenzene3NH liq. in
2NaNH (p) meso-2, 3-Dibromobutane
(B) cis-2-Butene 2Br (q) Benzyne mechanism
(C) trans-2-Butene 2Br (r) Bimolecular mechanism
(D) p-Nitrochlorobenzene
KOH .Aq (s) (±)-2, 3-Dibromobutane
OH H
C2H5
H
CHO
(1)
HO OH H
C2H5
H
CHO
(2)
HO
Cl
NO2
and
Cl
NO2
Cl
SO3H
and
Cl
NO2
Cl
NO2
and
NO2
Cl NO2
Cl
NO2
and NO2
Cl
Cl2/FeCl3
HNO3/H2SO4
A HNO3/H2SO4
B
C Cl2/FeCl3
D Below 330K
Cl
Cl2. h Cl2. h C6H12 (mol. wt. 84)
(A)
Cl Cl
+
Cl
Cl +
Cl
Cl
+
Cl
Cl
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a. A – p ; B – r; C – q ; D - s b. A – q ; B – s ; C – p ; D – r c. A – p ; B – r; C – s ; D – q d. A – q ; B – r, C – s ; D – p B Sol. A(chlorobenzene) – q(benzyne mechanism); B(cis-2-butene)-s ((±)-2, 3-dibromobutane); C(trans-2-butene)-p(meso-2, 3-dibromobutane); D(p-nitrochlorobenzene)-r-(bimolecular /mechanism). ArSN2
SECTION – B (ASSERTION & REASON) This Section contains 10 multiple choice questions. Each question has four choices A), B), C) and
D) out of which ONLY ONE is correct. (10 × 5 = 50 Marks)
(a) Statement -1 is True, Statement-2 is True; Statement-2 is a correct explanation for Statement-1
(b) Statement- 1 is True, Statement-2 is True; Statement-2 is NOT a correct explanation for Statement-1 (c) Statement-1 is True, Statement -2 is False (d) Statement – 1 is False, Statement-2 is True 1. Statement – 1: Nucleophilicity does not always match with basicity.
Statement – 2: While nucleophilcity is more related to size, polarizability and steric factors, the basicity is the ability to abstract a proton from a substrate & depend on stability of bond with hydrogen a. (a) b. (b) c. (c) d. (d) A
2. Statement– 1: CH3 – CH2 – CH2Br when treated with NaCN gives mainly the corresponding cyanide or nitrile. Statement – 2: Sodium cyanide have only one nucleophilic centre on carbon atom. a. (a) b. (b) c. (c) d. (d) C
Sol. C N is ambident Nucleophile.
3. Statement – 1: Fluorobenzene undergoes nucleophilic substitution much faster than chlorobenzene. Statement – 2: Fluorine being more electronegative causes more decrease in electron density at the carbon leading to a faster attack by the nucleophile & it also stablise intermediate formed after nucleophilic attack. a. (a) b. (b) c. (c) d. (d) A
4. Statement – 1: In Reimer Tiemann reaction of phenol only one aldehyde group will be introduced at either ortho & para position Statement – 2: Aldehyde group introduced after first RTR, will deactivate the ring for further Reimer
Tiemann’s reaction
a. (a) b. (b) c. (c) d. (d)
A
5. Statement – 1: Order of acidic strength of trihalomethane is:
CHCl3 > CHF3 > CHBr3 > CHI3
Statement – 2: Conjugate base of CHCl3 is resonance stabilized for, rest of the trihalide decrease in –I
effect will decrease the acidic strength.
a. (a) b. (b) c. (c) d. (d)
A
Dr. Sangeeta Khanna Ph.D
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6. Statement – 1: Aliphatic pri-amine are less reactive than aromatic pri.amine on reaction with CHCl3 &
alc. KOH
Statement – 2: Both give foul smelling isocyanide on reacting with CHCl3 & alc. KOH
a. (a) b. (b) c. (c) d. (d)
D
7. Statement – 1:
OH CHNCHCHPh
32
322
CHCH
CH CH CH
|
|322 on heating in presence of Ag2O give
vinylbenzene as major product
Statement – 2: Least acidic -hydrogen will be attacked by OH–. a. (a) b. (b) c. (c) d. (d) C
8. Assertion. CHBr = CHCl exhibits geometrical isomerism but CH2Br – CH2Cl does not. Reason. Geometrical isomerism arises due to restricted rotation about C = C double bond a. (A) b (B) c. (C) d. (D) A 9. Assertion. Twist boat conformation of cyclohexane is more stable than boat formation. Reason. Flagpole-flagpole interactions are less severe in boat conformation than in twist boat
conformation.
a. (A) b.(B) c. (C) d. (D)
C
10. Assertion. Stereoisomers which are not mirror images are called diastereomers.
Reason. Diastereomers may or may not be optically active.
a. (A) b. (B) c. (C) d. (D)
B
SECTION – C (Paragraph Type)
This Section contains 2 paragraph. Each of these questions has four choices A), B), C) and D) out of which ONLY ONE is correct. 9 × 4 = 36 Marks
Comprehension – 1 Since Grignard reagents resemble carbanion so they are strong nucleophile and strong base. Their most useful nucleophilic reaction is addition to carbonyl group.
X
OH
MgOHCRgXMOCROC gXMR/
\
|
|
HOHΘ|
|
Θ \
/
1. Which of the following compounds will not give acid-base reaction with RMgX?
a. CH3 – CH2 – Cl b. CH3OH c. NH3 d. H2S A
Sol. CH3CH2 – Cl give substitution reaction.
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2. Which of the following compounds give racemic mixture on reaction with H3C – MgBr?
a. H
O
CH| |
b. 3
| |
3 CH
O
CCH c. H
O
CPh| |
d. Cl
O
CCH| |
3
C
Sol. gBrMHC OCPh
H3
Θ\/
Racemic Product
3. What will be the final product in the following:
a. COOHCHH
CH
CCH 2|
3
3
b. COOHCHCHH
CH
CCH 22|
3
3
c. 3|
3 CHH
CNCH
CCH
2
d. CH3CH2CH2CH2COOH
B Sol. 4. Which of the following will give sec. alcohol with excess of grignard Reagent
a. 3||
3 CH
O
CCH b. HCOOC2H5 c. CH3COCl d. HCHO
B
Sol.
alcohol .sec
|
|HOH
RMgX||
|52
||
OH
R
R
CH
O
R
CHMgX -R HOC
O
CH
5. Which of the following is the final product of given reaction. a. b. c. d. D
CH3 – CH – Cl
CH3
(1) Mg dry
ether A
(2) O
(3) HOH (4) PCl5
B (5) KCN
(6) HOH D
CH3 – CH – CH3
Cl
Mg CH3 – CH – CH3
MgCl
O
HOH CH3 – CH – CH3
CH2CH2OH
(1) PCl5 (2) KCN
CH3 – CH – CH2 – CH2CN
CH3
HOH CH3 – CH – CH2 – CH2COOH
CH3
O
1. C2H5MgBr
2. HOH Product
CH2
OH
C2H5 H3C – C – C2H5
OH
CH3
CH3 – C – CH2 – CH2 – CH3
OH
CH3
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Sol.
Passage – 2
Under common reaction conditions, a carbocation rearranges to another carbocation of equal or
greater stability. For example, secondary carbocation will rearrange to a tertiary carbocation. It will not
rearrange to a less stable primary carbocation. This generalization is not absolute, and because there
is not a high energy barrier to the rearrangement of carbocations, rearrangement to a less stable cation
can occur if it offers the chance to form a more stable product.
6. In which of the following cations rearrangement takes place?
a. b. c. d.
D
Sol.
7. In which of the following cations rearrangement takes place most rapidly?
a. b. c. d.
A
Sol.
8. In the following cation, H/CH3 that is most likely to migrate to the positively charged carbon is:
35
3
|
|
4
|
3|
|
213 CH
H
CH
C
H
C
H
OH
CCH
a. CH3 at C – 4 b. H at C – 4 c. CH3 at C – 2 d. H at C – 2 D Sol.
9. 2,3-Dimethyl-2-butene can be prepared by heating which of the following compounds with a strong acid ?
a. (CH3)3C – CH = CH2 b. (CH3)2C = CH – CH2 – CH3
c. (CH3)2CH CH2 CH = CH2 d.
3
3 2 2|
(CH ) CH CH CH CH
CH
CH2 CH2
C – CH2
H
CH3
CH3 – C – CH2
H
CH3
CH2
CH2
C – CH2
H
CH3
Ph – C – CH2
CH3
CH3 C CH C CH3
CH3
H H
OH
CH3 C CH2 CH
OH
CH3
CH3
O
1. C2H5MgBr
2. HOH
C2H5
OH
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A
Sol.
SECTION – D (More than One Answer Type) No Negative Marking
This Section contains 10 multiple choice questions. Each question has four choices A), B), C) and
D) out of which One or More than one answer may be correct. 10 × 5 = 50 Marks
1. Which of the following are correct order of nucleophilicity?
a. 223 HNHNHN
b. Θ||
3
ΘΘ
23 O
O
CCHHOOCHCH
c. ΘΘΘΘ IBrClF d.
A,B,D 2. Which of the following are electrophiles?
a. BF3 b. 2CCl c. 4HN
d. ΘI
A,B
Sol. H
H
H
NH|
| Complete octet, not electrophilic.
3. Which of the following have asymmetric carbon atom? a. CH2Cl-CH2Br b. CH3-CHCl2 c. CH3-CHDCl d. CH2Br-CHOH-CH3 C, D
4. Which structure/s has (R) configuration ?
a. b. c. d. A,C 5. Which of the following will not give addition reaction with RMgX?
a. CO2 b. CH3 – CH2 – Br c. SO2 d. OH
O
CCH| |
3
B,D Sol. (b,d) (b) gives substitution reaction while (d) gives acid base reaction.
O > H3C – C H3CO O
O
H HO
CH2CH3
CH3
H
CH3 Et
Br
H
Cl
C2H5
C3H7
H
COOH HO
CH3
H+
-H+
H3C C CH = CH2 H3C C CH CH3
CH3
CH3
CH3
CH3
CH3 – shift H3C C CH CH3
CH3 CH3
H3C C = C CH3
CH3 CH3
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6. For an SN2 reaction, which of the following statements are true?
a. The rate of reaction is independent of the concentration of the nucleophile. b. The nucleophile attacks the C-atom on the side of the molecule opposite to the group being
displaced c. The reaction proceeds with simultaneous bond formation and rupture. d. More than one transition states are formed B,C
7. Which of the following are chiral?
a. O
CH
HC
PHC
3
56
|
|52 b. OS
CH
Ph
\/
3
c. H
CH
HC
NHC
3
56
|
|52 d. OS
CH
CH
\/
3
3
A, B, C 8. Which of the following is the correct order as indicated
a. FH
CH
CCH
3
|3 < CH3 – CH2 – CH2Cl < CH3 – CH2 – CH2 – Br (Boiling point)
b. CH3Cl < CH2Cl2 < CHCl3 < CCl4 (density) c. CH3Cl < CH3F < CH3Br < CH3I (density) d. CCl4 < CHCl3 < CH3Cl < CH2Cl2 (dipole-moment) A, B
9. Among the following pair of reactions in which pair second reaction is more reactive than first for SN1 reaction?
a. Me3C – Cl + H2O and Me3C – Br + H2O b. Me3C–Cl+CH3OH and Me3C – Cl + CH3COOH
c. OHClCMe 2)M1(
3 and OHClCMe 2)M2(
3 d. Me3C – Cl + CH3SH and Me3C – F + CH3SH
A,C 10. Predict the pair in which 2nd will undergo solvolysis (in aqueous ethanol) more rapidly.
(I) II I II a. b. c. d. B,C,D
Br Cl
Br Br
O
Br CH2Br Br Cl
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SECTION – E (Matrix Type) No Negative Marking
This Section contains 3 questions. Each question has four choices (A, B, C and D) given in Column I and five statements (p, q, r, and s) in Column II. Any given statement in Column I can have correct matching with one or more statement(s) given in Column II. 8 × 3 = 24 Marks
1. Match List – I with List – II (Single Match)
Column – I (Statement) Column – II (Reason)
(A) H2S is weaker nucleophile than HS
Θ
(p) Bulky group present on nucleophilic centre
decreases nucleophilicity
(B) 3
Θ
HC is stronger nucleophile than 2
Θ
HN (q) Nucleophilicity decreases on going from left
to right in the period of periodic table
(C)
PR3 is stronger nucleophile than
NR3 (r) A species with negative charge is a stronger
nucleophile than a similar species without a negative charge
(D) Θ
3
|3 OH
CH
CCH is weaker nucleophile than
Θ
3 O CH
(s) Nucleophilicity increases on going down in the group of the periodic table
Sol. A – r; B – q; C – s; D – p 2. Match the Column I with Column II.
Column I Column II
(A) CH3(CH2)3CN and (CH3)3CCN (p) Position isomers (B) CH3CH2CH2OCH3 and CH3CH2OCH2CH3 (q) Chain isomers (C) 3
3
|3 OCHH
CH
CCH and CH3CH2CH2 – O – CH3 (r) Functional isomers
(D)
CH2 = CH – OH and
(s) Metamers
Sol. A – (q); B – (s) or (q); C – (p), (s) ; D– (r) 3. Match Column (I) with Column (II)
(a) (p) Nucleophilic substitution (b) (q) Electrophilic substitution (c) (r) Cation intermediate (d) (s) Free radical substitution
Sol. A – (q), (r); B – (q), (r) ; C – (p), (r); D – (s)
O
+ Ph – CH2 – Cl AlCl3
CH2 – Ph
+ Ph Cl
O
AlCl3 C – Ph
O
H3C – C – CH3
CH3
CH3
Br2, hv CH3 – C – CH2 – Br
CH3
CH3
Br KOH (aq.) CH3 – C – CH3
OH CH3 CH3 H3C
CH3
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SECTION – F (Integer Type) No Negative Marking
This Section contains 10 questions. The answer to each question is a single digit integer ranging from 0 to 9. 10 × 5 = 50
1. The total number of methyl ‘CH3’ groups in the major product of reaction
3
3|
Na 3
Dry ether|
CH
CH C Cl
CH
Sol. 2 Tertiary alkyl halide gives alkene in Wurtz reaction.
3 2
3 3| |
Na 3 3
Dry ether| ||
CH CH
CH CH Cl CH C
CH CH
2. Total number of alkenes structure which will show geometrical isomerism of molecular formula C6H12. Sol. 4
(i) CH3 CH = CH CH2 CH2 CH3 (ii)
3
3 3|
CH CH CH CH CH
CH
(iii)
3
3 2 3|
CH CH C CH CH
CH
(iv) CH3 CH2 CH = CH CH2 CH3
[1-hexene; 2,3-dimethylbut-2-ene; 2,3-dimethylbut-1-ene; 2,2-dimethylbut-1-ene do not show geometrical isomer]
3. How many chiral carbons are there in Reserpine (in antipsychotic drug)?
Sol. 8
4. The number of possible enantiomeric pairs that can be produced during monochlorination of 2-methylbutane is
Sol. 2; 32
|
3 CHCHH
ClCH
CCH
2
; 3
||
3 CHH
Cl
CH
CH
CCH
3
O
O
O
O
N
N H
O
O
O O
O
O
O
O
O
N
O
O
O O
O
N H
C
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5. How many optical isomers are possible for the compound?
F
BrCl
C
Sol. 2 (single chiral) 6. How many meso isomers of C4H8Cl2 will be formed? Sol. Only one meso possible 7. How many of the following are good substrate for Both SN1 & SN2
(A) (B) CH3Cl (C) CH3 – O – CH2 – Br (D) CH2 = CH – CH2 – Cl
(E) ClCH
O
CCH 2
||
3 (F) (G) (F3C)3C – Cl (H)
Sol. 3; (A); (C); (D) 8. How many of the following give yellow ppt. with AgNO3 + aq.KOH
(A) CH2 = CH – Br (B) CH2 = CH – CH2Br (C) CH3 – CH2 – CH2I (D) (CH3)3C – Br (E) (F) CH3 – CH = CH – Br (G)
Sol. 4; (b); (c); (d), (g) 9. How many dimethyl cyclobutane will be possible (including stereoisomers)? Sol. 6 10. How many CH3MgBr molecules are required for the given molecule
Sol. 4
H – C – Cl
H – C – Cl
CH3
CH3
CH3
CH3
cis(meso) Trans (d, ) (3)
CH3
H3C
cis-trans (2)
CH3
CH3
(1)
HC C
CH
C
O
CH2
COOH
OH
CH2Cl
C Cl
C2H5
CH3
Cl
CH2Cl
CH2 – I
H – C C
CH
C
O
CH2
COOH
OH
acidic Acidic
electrophilic centre
acidic
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