Page 1
—
5 4 3 2 1
1. (b) : HC C — CH CH — CH 3
Pent-2-en-4-yne
(10 ?-bonds and 3?-bonds)
14. (a) :
2. (b) :
3. (d) : There are four double bonds. Hence, no. of
?-electrons = 2 × 4 = 8.
15. (a) :
CH
3
4
CH
3
2 1
4-Ethyl-3-propylhex-1-ene
4. (d) : C
7
H –
6
C – C
5
H CH–
3
CH –C CH
sp
3
3
sp
3
sp
2
sp
2
sp
3
sp sp
CH
3
? C 2 - sp, C 3 - sp
3
, C 5 - sp
2
and C 6 - sp
3
sp
3
sp
2
sp
2
sp
3
sp sp
16. (a) :
5. (d) : CH
3
CH CH CH
2
C CH 17. (b) :
6 5 4 3 2 1
The state of hybridisation of carbon in 1, 3 and 5 position
are sp, sp
3
and sp
2
.
6. (d) :
7. (d) :
8. (c) :
9. (a) : Tetrachloroethene being an alkene has sp
2
-
hybridised C-atoms and hence the angle Cl – C – Cl is
120° while in tetrachloromethane, carbon is sp
3
hybridised, therefore the angle Cl – C – Cl is 109°28???
10. (a) :
(C 6H 7O 2N)
Hence, it is homocyclic (as the ring system is made of
one type of atoms, i.e., carbon) but not aromatic.
11. (d) :
If a molecule contains both carbon-carbon double or
triple bonds, the two are treated as per in seeking the
lowest number combination. However, if the sum of
numbers turns out to be the same starting from either
of the carbon chain, then lowest number is given to the
C C double bond.
18. (c) :
Since the sum of numbers starting from either side of the
carbon chain turns out to be the same, so lowest number
is given to the C C end.
19. (c) :
It is 2,3-dimethylpentanoyl chloride.
20. (a) :
4-Ethyl-3-methylheptane
CH 3
12. (c) : CH 3 — CH — CH 2 —
(iso-butyl group)
13. (d) :
IUPAC name of the compound is
3- ethyl-2-hydroxy-4-methylhex-3-en-5-ynoic acid.
21. (a) :
22. (b) :
The double bond gets priority over triple bond. Therefore,
correct IUPAC name is 1-hexene-5-yne.
23. (a) :
C
E
Hints & Explanations
Page 2
—
5 4 3 2 1
1. (b) : HC C — CH CH — CH 3
Pent-2-en-4-yne
(10 ?-bonds and 3?-bonds)
14. (a) :
2. (b) :
3. (d) : There are four double bonds. Hence, no. of
?-electrons = 2 × 4 = 8.
15. (a) :
CH
3
4
CH
3
2 1
4-Ethyl-3-propylhex-1-ene
4. (d) : C
7
H –
6
C – C
5
H CH–
3
CH –C CH
sp
3
3
sp
3
sp
2
sp
2
sp
3
sp sp
CH
3
? C 2 - sp, C 3 - sp
3
, C 5 - sp
2
and C 6 - sp
3
sp
3
sp
2
sp
2
sp
3
sp sp
16. (a) :
5. (d) : CH
3
CH CH CH
2
C CH 17. (b) :
6 5 4 3 2 1
The state of hybridisation of carbon in 1, 3 and 5 position
are sp, sp
3
and sp
2
.
6. (d) :
7. (d) :
8. (c) :
9. (a) : Tetrachloroethene being an alkene has sp
2
-
hybridised C-atoms and hence the angle Cl – C – Cl is
120° while in tetrachloromethane, carbon is sp
3
hybridised, therefore the angle Cl – C – Cl is 109°28???
10. (a) :
(C 6H 7O 2N)
Hence, it is homocyclic (as the ring system is made of
one type of atoms, i.e., carbon) but not aromatic.
11. (d) :
If a molecule contains both carbon-carbon double or
triple bonds, the two are treated as per in seeking the
lowest number combination. However, if the sum of
numbers turns out to be the same starting from either
of the carbon chain, then lowest number is given to the
C C double bond.
18. (c) :
Since the sum of numbers starting from either side of the
carbon chain turns out to be the same, so lowest number
is given to the C C end.
19. (c) :
It is 2,3-dimethylpentanoyl chloride.
20. (a) :
4-Ethyl-3-methylheptane
CH 3
12. (c) : CH 3 — CH — CH 2 —
(iso-butyl group)
13. (d) :
IUPAC name of the compound is
3- ethyl-2-hydroxy-4-methylhex-3-en-5-ynoic acid.
21. (a) :
22. (b) :
The double bond gets priority over triple bond. Therefore,
correct IUPAC name is 1-hexene-5-yne.
23. (a) :
C
E
Hints & Explanations
The group should get priority over methyl group.
? Correct IUPAC name is
30. (c) : Enolic form of ethyl acetoacetate has 18
?-bonds and 2 ?-bonds.
31. (b)
32. (b) : Only four structural isomers are possible for
monochlorinated diphenylmethane.
24. (a) :
25. (a) :
As —COOH group is highest priority group, it is
numbered one. So, the IUPAC name is 3-amino-5-
heptenoic acid.
26. (b) :
27. (b) :
28. (a) : ?-Hydrogen at bridge carbon never participate
in tautomerism. Thus, only (III) exhibits tautomerism.
33. (b) : It is a special type of functional isomerism, in
which both the isomers are represented by one and the
same substance and are always present in equilibrium. It is
exhibited by nitroalkane (RCH 2NO 2) and isonitroalkane.
34. (a) : There are 7 isomers in C 4H 10O. Out of these, 4
are alcohols and 3 are ethers.
CH 3 CH 2 – O – CH 2 CH 3,
CH 3OCH 2 CH 2 CH 3,
CH 3 CH 2 CH 2 CH 2OH,
29. (b) : In keto-enol tautomerism,
(I)
here, ?-H participates.
(II)
35. (d) : Isomers must have same molecular formula
but different structural formula.
36. (b) : 5-chain isomers are obtained from alkane
C
6
H
14
.
(i) CH 3 CH 2 CH 2 CH 2 CH 2 CH 3
(ii)
(iii) (iv)
(v)
+
37. (d) : tert-Butyl carbocation, (CH3 )3 C
+
is more
here, ?-H participates.
stable than sec-butyl carbocation (CH 3)2CH due to
hyperco
+
njugation.
+
(III)
(CH 3) 3C has nine C — H bonds while (CH 3) 2CH has six
C — H bonds. Thus, there is more hyperconjugative
structures in tert-butyl carbocation.
38. (c) : Among the given carbocations,
here, ?-H participates (p-tautomerism). CH — C
+
H— CH — CH — CH is most stable
3 2 2 3
v
Page 3
—
5 4 3 2 1
1. (b) : HC C — CH CH — CH 3
Pent-2-en-4-yne
(10 ?-bonds and 3?-bonds)
14. (a) :
2. (b) :
3. (d) : There are four double bonds. Hence, no. of
?-electrons = 2 × 4 = 8.
15. (a) :
CH
3
4
CH
3
2 1
4-Ethyl-3-propylhex-1-ene
4. (d) : C
7
H –
6
C – C
5
H CH–
3
CH –C CH
sp
3
3
sp
3
sp
2
sp
2
sp
3
sp sp
CH
3
? C 2 - sp, C 3 - sp
3
, C 5 - sp
2
and C 6 - sp
3
sp
3
sp
2
sp
2
sp
3
sp sp
16. (a) :
5. (d) : CH
3
CH CH CH
2
C CH 17. (b) :
6 5 4 3 2 1
The state of hybridisation of carbon in 1, 3 and 5 position
are sp, sp
3
and sp
2
.
6. (d) :
7. (d) :
8. (c) :
9. (a) : Tetrachloroethene being an alkene has sp
2
-
hybridised C-atoms and hence the angle Cl – C – Cl is
120° while in tetrachloromethane, carbon is sp
3
hybridised, therefore the angle Cl – C – Cl is 109°28???
10. (a) :
(C 6H 7O 2N)
Hence, it is homocyclic (as the ring system is made of
one type of atoms, i.e., carbon) but not aromatic.
11. (d) :
If a molecule contains both carbon-carbon double or
triple bonds, the two are treated as per in seeking the
lowest number combination. However, if the sum of
numbers turns out to be the same starting from either
of the carbon chain, then lowest number is given to the
C C double bond.
18. (c) :
Since the sum of numbers starting from either side of the
carbon chain turns out to be the same, so lowest number
is given to the C C end.
19. (c) :
It is 2,3-dimethylpentanoyl chloride.
20. (a) :
4-Ethyl-3-methylheptane
CH 3
12. (c) : CH 3 — CH — CH 2 —
(iso-butyl group)
13. (d) :
IUPAC name of the compound is
3- ethyl-2-hydroxy-4-methylhex-3-en-5-ynoic acid.
21. (a) :
22. (b) :
The double bond gets priority over triple bond. Therefore,
correct IUPAC name is 1-hexene-5-yne.
23. (a) :
C
E
Hints & Explanations
The group should get priority over methyl group.
? Correct IUPAC name is
30. (c) : Enolic form of ethyl acetoacetate has 18
?-bonds and 2 ?-bonds.
31. (b)
32. (b) : Only four structural isomers are possible for
monochlorinated diphenylmethane.
24. (a) :
25. (a) :
As —COOH group is highest priority group, it is
numbered one. So, the IUPAC name is 3-amino-5-
heptenoic acid.
26. (b) :
27. (b) :
28. (a) : ?-Hydrogen at bridge carbon never participate
in tautomerism. Thus, only (III) exhibits tautomerism.
33. (b) : It is a special type of functional isomerism, in
which both the isomers are represented by one and the
same substance and are always present in equilibrium. It is
exhibited by nitroalkane (RCH 2NO 2) and isonitroalkane.
34. (a) : There are 7 isomers in C 4H 10O. Out of these, 4
are alcohols and 3 are ethers.
CH 3 CH 2 – O – CH 2 CH 3,
CH 3OCH 2 CH 2 CH 3,
CH 3 CH 2 CH 2 CH 2OH,
29. (b) : In keto-enol tautomerism,
(I)
here, ?-H participates.
(II)
35. (d) : Isomers must have same molecular formula
but different structural formula.
36. (b) : 5-chain isomers are obtained from alkane
C
6
H
14
.
(i) CH 3 CH 2 CH 2 CH 2 CH 2 CH 3
(ii)
(iii) (iv)
(v)
+
37. (d) : tert-Butyl carbocation, (CH3 )3 C
+
is more
here, ?-H participates.
stable than sec-butyl carbocation (CH 3)2CH due to
hyperco
+
njugation.
+
(III)
(CH 3) 3C has nine C — H bonds while (CH 3) 2CH has six
C — H bonds. Thus, there is more hyperconjugative
structures in tert-butyl carbocation.
38. (c) : Among the given carbocations,
here, ?-H participates (p-tautomerism). CH — C
+
H— CH — CH — CH is most stable
3 2 2 3
v
Organic Chemistry - Some Basic Principles and Techniques
carbocation. As is consists of maximum number of
?-hydrogens and stablised by hyperconjugation.
39. (a, b) : –I effect increases on increasing the
electronegativity of atom.
? – NH 2 < – OR < – F ( –I effect)
Also, – NR 2 < – OR < – F (–I effect)
40. (c) : –NO 2 group is meta-directing, thus will
stabilize a electrophile at m-position.
41. (c)
42. (d) : Nucleophiles are electron rich species hence,
they are Lewis bases.
43. (c) :
44. (a) : Nucleophile will attack a stable carbocation
(S N1 reaction).
45. (a) : Hyperconjugation can occur only in compound
III as it has ?-hydrogen atom.
46. (d) : is most stable due to
hyperconjugation.
47. (c)
48. (a) : Greater the number of electron donating alkyl
groups (+I effect), greater is the stability of carbocations.
+I effect is in the order :
More the number of hyperconjugative structures of
carbocations, more is the stability.
Hence, the order of stability of carbocations is
5 < 4 < 3 < 1 < 2.
49. (a)
50. (b) : More the number of hyperconjugative
structures, the greater is the stability.
51. (c) : Nucleophilic substitution reaction involves the
displacement of a nucleophile by another.
52. (b) : +R effect of —OH group is greater than that
o f —OCH 3 group.
53. (c)
54. (c) : Higher the no. of electron releasing groups
lower will be stability of carbanion, and vice-versa. So,
the order of stability of carbanions is
55. (a) : In case of different nucleophiles, but present in
the same group in the periodic table, then larger is the
atomic mass, higher is the nucleophilicity. Hence, the
increasing order of nucleophilicity of the halide ions is
F
–
< Cl
–
< Br
–
< I
–
.
56. (d) :
3° carbon is more stable due to the stabilization of the
charge by three methyl groups (or +I
–
effect). It can also
be explained on the basis of hyperconjugation. Greater
the number of hyperconjugative ?-H atoms, more will
be the hyperconjugative structures and more will be the
stability.
57. (c) : 3º > 2º > 1º more the delocalisation of positive
charge, more is its stability.
58. (d) : All the properties mentioned in the question
suggest that it is a benzene molecule. Since in benzene all
carbons are sp
2
-hybridised, therefore, C – C – C angle is
120º.
59. (b) : Paper chromatography is a type of partition
chromatography.
60. (c) : T he o- and p-nitrophenols are separated by
steam distillation since o-isomer is steam volatile due to
intramolecular H-bonding while p-isomer is not steam
volatile due to association of molecules by intermolecular
H-bonding.
Page 4
—
5 4 3 2 1
1. (b) : HC C — CH CH — CH 3
Pent-2-en-4-yne
(10 ?-bonds and 3?-bonds)
14. (a) :
2. (b) :
3. (d) : There are four double bonds. Hence, no. of
?-electrons = 2 × 4 = 8.
15. (a) :
CH
3
4
CH
3
2 1
4-Ethyl-3-propylhex-1-ene
4. (d) : C
7
H –
6
C – C
5
H CH–
3
CH –C CH
sp
3
3
sp
3
sp
2
sp
2
sp
3
sp sp
CH
3
? C 2 - sp, C 3 - sp
3
, C 5 - sp
2
and C 6 - sp
3
sp
3
sp
2
sp
2
sp
3
sp sp
16. (a) :
5. (d) : CH
3
CH CH CH
2
C CH 17. (b) :
6 5 4 3 2 1
The state of hybridisation of carbon in 1, 3 and 5 position
are sp, sp
3
and sp
2
.
6. (d) :
7. (d) :
8. (c) :
9. (a) : Tetrachloroethene being an alkene has sp
2
-
hybridised C-atoms and hence the angle Cl – C – Cl is
120° while in tetrachloromethane, carbon is sp
3
hybridised, therefore the angle Cl – C – Cl is 109°28???
10. (a) :
(C 6H 7O 2N)
Hence, it is homocyclic (as the ring system is made of
one type of atoms, i.e., carbon) but not aromatic.
11. (d) :
If a molecule contains both carbon-carbon double or
triple bonds, the two are treated as per in seeking the
lowest number combination. However, if the sum of
numbers turns out to be the same starting from either
of the carbon chain, then lowest number is given to the
C C double bond.
18. (c) :
Since the sum of numbers starting from either side of the
carbon chain turns out to be the same, so lowest number
is given to the C C end.
19. (c) :
It is 2,3-dimethylpentanoyl chloride.
20. (a) :
4-Ethyl-3-methylheptane
CH 3
12. (c) : CH 3 — CH — CH 2 —
(iso-butyl group)
13. (d) :
IUPAC name of the compound is
3- ethyl-2-hydroxy-4-methylhex-3-en-5-ynoic acid.
21. (a) :
22. (b) :
The double bond gets priority over triple bond. Therefore,
correct IUPAC name is 1-hexene-5-yne.
23. (a) :
C
E
Hints & Explanations
The group should get priority over methyl group.
? Correct IUPAC name is
30. (c) : Enolic form of ethyl acetoacetate has 18
?-bonds and 2 ?-bonds.
31. (b)
32. (b) : Only four structural isomers are possible for
monochlorinated diphenylmethane.
24. (a) :
25. (a) :
As —COOH group is highest priority group, it is
numbered one. So, the IUPAC name is 3-amino-5-
heptenoic acid.
26. (b) :
27. (b) :
28. (a) : ?-Hydrogen at bridge carbon never participate
in tautomerism. Thus, only (III) exhibits tautomerism.
33. (b) : It is a special type of functional isomerism, in
which both the isomers are represented by one and the
same substance and are always present in equilibrium. It is
exhibited by nitroalkane (RCH 2NO 2) and isonitroalkane.
34. (a) : There are 7 isomers in C 4H 10O. Out of these, 4
are alcohols and 3 are ethers.
CH 3 CH 2 – O – CH 2 CH 3,
CH 3OCH 2 CH 2 CH 3,
CH 3 CH 2 CH 2 CH 2OH,
29. (b) : In keto-enol tautomerism,
(I)
here, ?-H participates.
(II)
35. (d) : Isomers must have same molecular formula
but different structural formula.
36. (b) : 5-chain isomers are obtained from alkane
C
6
H
14
.
(i) CH 3 CH 2 CH 2 CH 2 CH 2 CH 3
(ii)
(iii) (iv)
(v)
+
37. (d) : tert-Butyl carbocation, (CH3 )3 C
+
is more
here, ?-H participates.
stable than sec-butyl carbocation (CH 3)2CH due to
hyperco
+
njugation.
+
(III)
(CH 3) 3C has nine C — H bonds while (CH 3) 2CH has six
C — H bonds. Thus, there is more hyperconjugative
structures in tert-butyl carbocation.
38. (c) : Among the given carbocations,
here, ?-H participates (p-tautomerism). CH — C
+
H— CH — CH — CH is most stable
3 2 2 3
v
Organic Chemistry - Some Basic Principles and Techniques
carbocation. As is consists of maximum number of
?-hydrogens and stablised by hyperconjugation.
39. (a, b) : –I effect increases on increasing the
electronegativity of atom.
? – NH 2 < – OR < – F ( –I effect)
Also, – NR 2 < – OR < – F (–I effect)
40. (c) : –NO 2 group is meta-directing, thus will
stabilize a electrophile at m-position.
41. (c)
42. (d) : Nucleophiles are electron rich species hence,
they are Lewis bases.
43. (c) :
44. (a) : Nucleophile will attack a stable carbocation
(S N1 reaction).
45. (a) : Hyperconjugation can occur only in compound
III as it has ?-hydrogen atom.
46. (d) : is most stable due to
hyperconjugation.
47. (c)
48. (a) : Greater the number of electron donating alkyl
groups (+I effect), greater is the stability of carbocations.
+I effect is in the order :
More the number of hyperconjugative structures of
carbocations, more is the stability.
Hence, the order of stability of carbocations is
5 < 4 < 3 < 1 < 2.
49. (a)
50. (b) : More the number of hyperconjugative
structures, the greater is the stability.
51. (c) : Nucleophilic substitution reaction involves the
displacement of a nucleophile by another.
52. (b) : +R effect of —OH group is greater than that
o f —OCH 3 group.
53. (c)
54. (c) : Higher the no. of electron releasing groups
lower will be stability of carbanion, and vice-versa. So,
the order of stability of carbanions is
55. (a) : In case of different nucleophiles, but present in
the same group in the periodic table, then larger is the
atomic mass, higher is the nucleophilicity. Hence, the
increasing order of nucleophilicity of the halide ions is
F
–
< Cl
–
< Br
–
< I
–
.
56. (d) :
3° carbon is more stable due to the stabilization of the
charge by three methyl groups (or +I
–
effect). It can also
be explained on the basis of hyperconjugation. Greater
the number of hyperconjugative ?-H atoms, more will
be the hyperconjugative structures and more will be the
stability.
57. (c) : 3º > 2º > 1º more the delocalisation of positive
charge, more is its stability.
58. (d) : All the properties mentioned in the question
suggest that it is a benzene molecule. Since in benzene all
carbons are sp
2
-hybridised, therefore, C – C – C angle is
120º.
59. (b) : Paper chromatography is a type of partition
chromatography.
60. (c) : T he o- and p-nitrophenols are separated by
steam distillation since o-isomer is steam volatile due to
intramolecular H-bonding while p-isomer is not steam
volatile due to association of molecules by intermolecular
H-bonding.
2
2
61. (b) : Sublimation method is used for those organ P
1
V
1
?
P
2
V
2
substances which pass directly from solid to vapour state
on heating and vice-versa on cooling e.g. benzoic acid,
naphthalene, camphor, anthracene, etc. Naphthalene
is volatile and benzoic acid is non-volatile due to the
T
1
V ?
P
1
V
1
T
2
T
1
P
2
T
2
?
700 ? 40 ? 273
300 ? 760
? 33.52 mL
formation of the dimer.
22400 mL of N 2 at STP weighs = 28 g
62. (b) : In steam distillation of toluene, the pressure
of toluene in vapour is less than pressure of barometer,
because it is carried out when a solid or liquid is insoluble
in water and is volatile with steam but the impurities are
? 33.52 mL of N 2
at STP weighs =
28 ? 33.52
22400
= 0.0419 g
non-volatile.
63. (d) : In the IR spectroscopy, each functional group
appears at a certain peak (in cm
–1
). So, cyclohexanone
can be identified by carbonyl peak.
64. (b) : 3Na 4[Fe(CN) 6] + 2Fe 2(SO 4) 3
Sodium ferrocyanide
Fe 4[Fe(CN) 6] 3 + 6Na 2SO 4
Ferric ferrocyanide
(Prussian blue)
65. (a) : In case of Lassaigne’s test of halogens, it is
% of N ?
??Mass of nitrogen at STP
? 100
Mass of organic compound taken
?
0.0419
? 100 ? 16.76%
0.25
70. (a) : H 2SO 4 + 2NH 3 ? (NH 4) 2SO 4
10 mL of 1 M H 2SO 4 = 10 mmol
[ M × V (mL) = mmol]
Acid used for the absorption of ammonia
= 10 mL of 2 N (or 1 M) H 2SO 4
% of N =
1.4 ? N ? V
?
1.4 ? 2 ? 10
? 37.33%
necessary to remove sodium cyanide and sodium
sulphide from the sodium extract if nitrogen and sulphur
W 0.75
are present. This is done by boiling the sodium extract
with conc. HNO 3.
NaCN + HNO 3 ? NaNO 3 + HCN ? ?
Na 2S + 2HNO 3 ? 2NaNO 3 + H 2S ? ?
66. (b) : Sodium cyanide (Na + C + N ? NaCN).
67. (d)
68. (b) : 2CuSO 4 + K 4[Fe(CN) 6] ? Cu 2[Fe(CN) 6]
chocolate ppt.
71. (b) : Given : V 1 = 55 mL, V 2 = ?
P 1 = 715 – 15 = 700 mm, P 2 = 760 mm
T 1 = 300 K, T 2 = 273 K
General gas equation,
P
1
V
1
?
P
2
V
2
T
1
T
2
Volume of nitrogen at STP,
V ?
P 1V 1T 2
?
700 ? 55 ? 273
? 46.099 mL
P 2 T 1 760 ? 300
69. (a) : Mass of organic compound = 0.25 g
Experimental values, At STP
+ 2K 2 SO 4
% of nitrogen =
V
2
8W
compound.
, where W = the mass of organic
V 1 = 40 mL, V 2 = ?
T 1 = 300 K, T 2 = 273 K
P 1 = 725 – 25 = 700 mm, P 2 = 760 mm
% of N =
46.099
? 16.46
8 ? 0.35
72. (a)
??? ?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
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