Organic Chemistry: Some Basic Principles and Techniques Practice

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NEET Chemistry - Chapter 13

Organic Chemistry: Some Basic Principles and Techniques Practice Tests

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Organic scope
1. Organic chemistry mainly deals with compounds of:
- A. carbon (Correct)
- B. oxygen only
- C. metals only
- D. silicon only
Explanation: Most organic compounds are carbon compounds.
Homologous series
2. Members of a homologous series differ by:
- A. $-CH_2-$ unit (Correct)
- B. an oxygen atom
- C. a nitrogen atom
- D. a proton
Explanation: Successive members differ by one methylene group.
Isomerism
3. Compounds with same molecular formula but different structures are:
- A. isomers (Correct)
- B. allotropes
- C. isotopes
- D. resonance forms
Explanation: Isomerism is central to organic chemistry.
Hybridization
4. Carbon in alkanes is generally:
- A. sp$^3$ hybridized (Correct)
- B. sp$^2$ hybridized
- C. sp hybridized
- D. unhybridized
Explanation: Single-bonded tetrahedral carbon is sp$^3$.
Inductive effect
5. Inductive effect is transmitted through:
- A. sigma bonds (Correct)
- B. pi bonds only
- C. hydrogen bonds
- D. metallic bonding
Explanation: It is a permanent electron-withdrawing or donating effect through sigma bonds.
Resonance
6. Resonance stabilizes molecules by:
- A. delocalizing electrons (Correct)
- B. increasing mass
- C. removing bonds
- D. fixing atoms in one position
Explanation: Electron delocalization lowers energy.
Carbocation
7. A carbocation is generally:
- A. electron-deficient (Correct)
- B. electron-rich
- C. neutral radical only
- D. always aromatic
Explanation: It has only six electrons around the positively charged carbon.
Stability
8. Order of carbocation stability is usually:
- A. 3$^\circ$ > 2$^\circ$ > 1$^\circ$ > methyl (Correct)
- B. methyl > 1$^\circ$ > 2$^\circ$ > 3$^\circ$
- C. 1$^\circ$ > 2$^\circ$ > 3$^\circ$
- D. all equal
Explanation: Hyperconjugation and inductive effects stabilize higher carbocations.
Carbanion
9. Order of carbanion stability is usually:
- A. methyl > 1$^\circ$ > 2$^\circ$ > 3$^\circ$ (Correct)
- B. 3$^\circ$ > 2$^\circ$ > 1$^\circ$
- C. all equal
- D. benzyl < methyl
Explanation: Alkyl groups destabilize a negatively charged carbon.
Radicals
10. Order of free-radical stability is generally:
- A. 3$^\circ$ > 2$^\circ$ > 1$^\circ$ > methyl (Correct)
- B. methyl > 1$^\circ$ > 2$^\circ$ > 3$^\circ$
- C. all equal
- D. 1$^\circ$ > 3$^\circ$
Explanation: Hyperconjugation stabilizes alkyl radicals too.
Electrophile
11. An electrophile is an electron-pair:
- A. acceptor (Correct)
- B. donor
- C. neutralizer
- D. buffer
Explanation: Electrophiles are electron-deficient species.
Nucleophile
12. A nucleophile is an electron-pair:
- A. donor (Correct)
- B. acceptor
- C. oxidiser
- D. reagent with zero electrons
Explanation: Nucleophiles are electron-rich species.
Reaction type
13. Substitution reactions involve:
- A. replacement of one atom or group by another (Correct)
- B. addition across multiple bond
- C. removal of small molecule only
- D. polymer formation always
Explanation: Substitution swaps one group for another.
Reaction type
14. Addition reactions are common in:
- A. unsaturated compounds (Correct)
- B. alkali metals
- C. noble gases
- D. saturated hydrocarbons only
Explanation: Double or triple bonds open up for addition.
Reaction type
15. Elimination reactions generally produce:
- A. multiple bonds (Correct)
- B. only single bonds
- C. salts only
- D. always alcohols
Explanation: Removal of atoms or groups creates unsaturation.
Reaction intermediate
16. The most stable resonance-stabilized carbocation among common examples is:
- A. benzyl carbocation (Correct)
- B. methyl carbocation
- C. vinyl carbocation
- D. ethyl carbocation
Explanation: Resonance disperses the positive charge over the ring.
Purification
17. Separation of liquids based on difference in boiling points is:
- A. distillation (Correct)
- B. crystallisation
- C. sublimation
- D. filtration
Explanation: This is the standard purification method for volatile liquids.
Purification
18. Steam distillation is used for compounds that are:
- A. volatile with steam and immiscible with water (Correct)
- B. ionic solids
- C. non-volatile salts
- D. always gaseous
Explanation: It allows lower-temperature distillation.
Qualitative analysis
19. The Lassaigne test is used in organic chemistry to detect:
- A. heteroatoms like N, S, and halogens (Correct)
- B. carbon only
- C. hydrogen only
- D. boiling point
Explanation: Sodium fusion converts them into ionic forms for testing.
IUPAC naming
20. Longest-chain selection is the first major step in:
- A. IUPAC nomenclature (Correct)
- B. resonance analysis
- C. electrophilic substitution
- D. steam distillation
Explanation: Naming begins by choosing the parent carbon chain.
Acid-base
21. A +I group generally:
- A. pushes electron density through sigma bonds (Correct)
- B. withdraws electron density strongly
- C. breaks all pi bonds
- D. creates aromaticity
Explanation: Electron-donating inductive groups show +I effect.
Acid-base
22. A -I group generally:
- A. withdraws electron density through sigma bonds (Correct)
- B. donates electrons to cations
- C. eliminates lone pairs
- D. always increases basicity
Explanation: Electron-withdrawing groups show -I effect.
Hyperconjugation
23. Hyperconjugation is often described as:
- A. no-bond resonance involving sigma electrons (Correct)
- B. pi bond breaking only
- C. hydrogen bonding inside molecule
- D. ionic delocalization in salts
Explanation: It helps explain stability of carbocations and alkenes.
Tautomerism
24. Keto-enol tautomerism involves migration of:
- A. proton and pi bond (Correct)
- B. carbon atom
- C. halogen atom
- D. whole alkyl group
Explanation: A proton shifts and the double bond relocates.
Organic logic
25. The cleanest way to solve many organic basics questions is to track electron flow through effects, intermediates, and:
- A. reaction type (Correct)
- B. osmotic pressure
- C. periodic group number
- D. standard potential
Explanation: That framework organizes most NEET organic logic.
Organic scope
26. Organic chemistry mainly deals with compounds of:
- A. carbon (Correct)
- B. oxygen only
- C. metals only
- D. silicon only
Explanation: Most organic compounds are carbon compounds.
Homologous series
27. Members of a homologous series differ by:
- A. $-CH_2-$ unit (Correct)
- B. an oxygen atom
- C. a nitrogen atom
- D. a proton
Explanation: Successive members differ by one methylene group.
Isomerism
28. Compounds with same molecular formula but different structures are:
- A. isomers (Correct)
- B. allotropes
- C. isotopes
- D. resonance forms
Explanation: Isomerism is central to organic chemistry.
Hybridization
29. Carbon in alkanes is generally:
- A. sp$^3$ hybridized (Correct)
- B. sp$^2$ hybridized
- C. sp hybridized
- D. unhybridized
Explanation: Single-bonded tetrahedral carbon is sp$^3$.
Inductive effect
30. Inductive effect is transmitted through:
- A. sigma bonds (Correct)
- B. pi bonds only
- C. hydrogen bonds
- D. metallic bonding
Explanation: It is a permanent electron-withdrawing or donating effect through sigma bonds.
Resonance
31. Resonance stabilizes molecules by:
- A. delocalizing electrons (Correct)
- B. increasing mass
- C. removing bonds
- D. fixing atoms in one position
Explanation: Electron delocalization lowers energy.
Carbocation
32. A carbocation is generally:
- A. electron-deficient (Correct)
- B. electron-rich
- C. neutral radical only
- D. always aromatic
Explanation: It has only six electrons around the positively charged carbon.
Stability
33. Order of carbocation stability is usually:
- A. 3$^\circ$ > 2$^\circ$ > 1$^\circ$ > methyl (Correct)
- B. methyl > 1$^\circ$ > 2$^\circ$ > 3$^\circ$
- C. 1$^\circ$ > 2$^\circ$ > 3$^\circ$
- D. all equal
Explanation: Hyperconjugation and inductive effects stabilize higher carbocations.
Carbanion
34. Order of carbanion stability is usually:
- A. methyl > 1$^\circ$ > 2$^\circ$ > 3$^\circ$ (Correct)
- B. 3$^\circ$ > 2$^\circ$ > 1$^\circ$
- C. all equal
- D. benzyl < methyl
Explanation: Alkyl groups destabilize a negatively charged carbon.
Radicals
35. Order of free-radical stability is generally:
- A. 3$^\circ$ > 2$^\circ$ > 1$^\circ$ > methyl (Correct)
- B. methyl > 1$^\circ$ > 2$^\circ$ > 3$^\circ$
- C. all equal
- D. 1$^\circ$ > 3$^\circ$
Explanation: Hyperconjugation stabilizes alkyl radicals too.
Electrophile
36. An electrophile is an electron-pair:
- A. acceptor (Correct)
- B. donor
- C. neutralizer
- D. buffer
Explanation: Electrophiles are electron-deficient species.
Nucleophile
37. A nucleophile is an electron-pair:
- A. donor (Correct)
- B. acceptor
- C. oxidiser
- D. reagent with zero electrons
Explanation: Nucleophiles are electron-rich species.
Reaction type
38. Substitution reactions involve:
- A. replacement of one atom or group by another (Correct)
- B. addition across multiple bond
- C. removal of small molecule only
- D. polymer formation always
Explanation: Substitution swaps one group for another.
Reaction type
39. Addition reactions are common in:
- A. unsaturated compounds (Correct)
- B. alkali metals
- C. noble gases
- D. saturated hydrocarbons only
Explanation: Double or triple bonds open up for addition.
Reaction type
40. Elimination reactions generally produce:
- A. multiple bonds (Correct)
- B. only single bonds
- C. salts only
- D. always alcohols
Explanation: Removal of atoms or groups creates unsaturation.
Reaction intermediate
41. The most stable resonance-stabilized carbocation among common examples is:
- A. benzyl carbocation (Correct)
- B. methyl carbocation
- C. vinyl carbocation
- D. ethyl carbocation
Explanation: Resonance disperses the positive charge over the ring.
Purification
42. Separation of liquids based on difference in boiling points is:
- A. distillation (Correct)
- B. crystallisation
- C. sublimation
- D. filtration
Explanation: This is the standard purification method for volatile liquids.
Purification
43. Steam distillation is used for compounds that are:
- A. volatile with steam and immiscible with water (Correct)
- B. ionic solids
- C. non-volatile salts
- D. always gaseous
Explanation: It allows lower-temperature distillation.
Qualitative analysis
44. The Lassaigne test is used in organic chemistry to detect:
- A. heteroatoms like N, S, and halogens (Correct)
- B. carbon only
- C. hydrogen only
- D. boiling point
Explanation: Sodium fusion converts them into ionic forms for testing.
IUPAC naming
45. Longest-chain selection is the first major step in:
- A. IUPAC nomenclature (Correct)
- B. resonance analysis
- C. electrophilic substitution
- D. steam distillation
Explanation: Naming begins by choosing the parent carbon chain.
Acid-base
46. A +I group generally:
- A. pushes electron density through sigma bonds (Correct)
- B. withdraws electron density strongly
- C. breaks all pi bonds
- D. creates aromaticity
Explanation: Electron-donating inductive groups show +I effect.
Acid-base
47. A -I group generally:
- A. withdraws electron density through sigma bonds (Correct)
- B. donates electrons to cations
- C. eliminates lone pairs
- D. always increases basicity
Explanation: Electron-withdrawing groups show -I effect.
Hyperconjugation
48. Hyperconjugation is often described as:
- A. no-bond resonance involving sigma electrons (Correct)
- B. pi bond breaking only
- C. hydrogen bonding inside molecule
- D. ionic delocalization in salts
Explanation: It helps explain stability of carbocations and alkenes.
Tautomerism
49. Keto-enol tautomerism involves migration of:
- A. proton and pi bond (Correct)
- B. carbon atom
- C. halogen atom
- D. whole alkyl group
Explanation: A proton shifts and the double bond relocates.
Organic logic
50. The cleanest way to solve many organic basics questions is to track electron flow through effects, intermediates, and:
- A. reaction type (Correct)
- B. osmotic pressure
- C. periodic group number
- D. standard potential
Explanation: That framework organizes most NEET organic logic.
Organic scope
51. Organic chemistry mainly deals with compounds of:
- A. carbon (Correct)
- B. oxygen only
- C. metals only
- D. silicon only
Explanation: Most organic compounds are carbon compounds.
Homologous series
52. Members of a homologous series differ by:
- A. $-CH_2-$ unit (Correct)
- B. an oxygen atom
- C. a nitrogen atom
- D. a proton
Explanation: Successive members differ by one methylene group.
Isomerism
53. Compounds with same molecular formula but different structures are:
- A. isomers (Correct)
- B. allotropes
- C. isotopes
- D. resonance forms
Explanation: Isomerism is central to organic chemistry.
Hybridization
54. Carbon in alkanes is generally:
- A. sp$^3$ hybridized (Correct)
- B. sp$^2$ hybridized
- C. sp hybridized
- D. unhybridized
Explanation: Single-bonded tetrahedral carbon is sp$^3$.
Inductive effect
55. Inductive effect is transmitted through:
- A. sigma bonds (Correct)
- B. pi bonds only
- C. hydrogen bonds
- D. metallic bonding
Explanation: It is a permanent electron-withdrawing or donating effect through sigma bonds.
Resonance
56. Resonance stabilizes molecules by:
- A. delocalizing electrons (Correct)
- B. increasing mass
- C. removing bonds
- D. fixing atoms in one position
Explanation: Electron delocalization lowers energy.
Carbocation
57. A carbocation is generally:
- A. electron-deficient (Correct)
- B. electron-rich
- C. neutral radical only
- D. always aromatic
Explanation: It has only six electrons around the positively charged carbon.
Stability
58. Order of carbocation stability is usually:
- A. 3$^\circ$ > 2$^\circ$ > 1$^\circ$ > methyl (Correct)
- B. methyl > 1$^\circ$ > 2$^\circ$ > 3$^\circ$
- C. 1$^\circ$ > 2$^\circ$ > 3$^\circ$
- D. all equal
Explanation: Hyperconjugation and inductive effects stabilize higher carbocations.
Carbanion
59. Order of carbanion stability is usually:
- A. methyl > 1$^\circ$ > 2$^\circ$ > 3$^\circ$ (Correct)
- B. 3$^\circ$ > 2$^\circ$ > 1$^\circ$
- C. all equal
- D. benzyl < methyl
Explanation: Alkyl groups destabilize a negatively charged carbon.
Radicals
60. Order of free-radical stability is generally:
- A. 3$^\circ$ > 2$^\circ$ > 1$^\circ$ > methyl (Correct)
- B. methyl > 1$^\circ$ > 2$^\circ$ > 3$^\circ$
- C. all equal
- D. 1$^\circ$ > 3$^\circ$
Explanation: Hyperconjugation stabilizes alkyl radicals too.
Electrophile
61. An electrophile is an electron-pair:
- A. acceptor (Correct)
- B. donor
- C. neutralizer
- D. buffer
Explanation: Electrophiles are electron-deficient species.
Nucleophile
62. A nucleophile is an electron-pair:
- A. donor (Correct)
- B. acceptor
- C. oxidiser
- D. reagent with zero electrons
Explanation: Nucleophiles are electron-rich species.
Reaction type
63. Substitution reactions involve:
- A. replacement of one atom or group by another (Correct)
- B. addition across multiple bond
- C. removal of small molecule only
- D. polymer formation always
Explanation: Substitution swaps one group for another.
Reaction type
64. Addition reactions are common in:
- A. unsaturated compounds (Correct)
- B. alkali metals
- C. noble gases
- D. saturated hydrocarbons only
Explanation: Double or triple bonds open up for addition.
Reaction type
65. Elimination reactions generally produce:
- A. multiple bonds (Correct)
- B. only single bonds
- C. salts only
- D. always alcohols
Explanation: Removal of atoms or groups creates unsaturation.
Reaction intermediate
66. The most stable resonance-stabilized carbocation among common examples is:
- A. benzyl carbocation (Correct)
- B. methyl carbocation
- C. vinyl carbocation
- D. ethyl carbocation
Explanation: Resonance disperses the positive charge over the ring.
Purification
67. Separation of liquids based on difference in boiling points is:
- A. distillation (Correct)
- B. crystallisation
- C. sublimation
- D. filtration
Explanation: This is the standard purification method for volatile liquids.
Purification
68. Steam distillation is used for compounds that are:
- A. volatile with steam and immiscible with water (Correct)
- B. ionic solids
- C. non-volatile salts
- D. always gaseous
Explanation: It allows lower-temperature distillation.
Qualitative analysis
69. The Lassaigne test is used in organic chemistry to detect:
- A. heteroatoms like N, S, and halogens (Correct)
- B. carbon only
- C. hydrogen only
- D. boiling point
Explanation: Sodium fusion converts them into ionic forms for testing.
IUPAC naming
70. Longest-chain selection is the first major step in:
- A. IUPAC nomenclature (Correct)
- B. resonance analysis
- C. electrophilic substitution
- D. steam distillation
Explanation: Naming begins by choosing the parent carbon chain.
Acid-base
71. A +I group generally:
- A. pushes electron density through sigma bonds (Correct)
- B. withdraws electron density strongly
- C. breaks all pi bonds
- D. creates aromaticity
Explanation: Electron-donating inductive groups show +I effect.
Acid-base
72. A -I group generally:
- A. withdraws electron density through sigma bonds (Correct)
- B. donates electrons to cations
- C. eliminates lone pairs
- D. always increases basicity
Explanation: Electron-withdrawing groups show -I effect.
Hyperconjugation
73. Hyperconjugation is often described as:
- A. no-bond resonance involving sigma electrons (Correct)
- B. pi bond breaking only
- C. hydrogen bonding inside molecule
- D. ionic delocalization in salts
Explanation: It helps explain stability of carbocations and alkenes.
Tautomerism
74. Keto-enol tautomerism involves migration of:
- A. proton and pi bond (Correct)
- B. carbon atom
- C. halogen atom
- D. whole alkyl group
Explanation: A proton shifts and the double bond relocates.
Organic logic
75. The cleanest way to solve many organic basics questions is to track electron flow through effects, intermediates, and:
- A. reaction type (Correct)
- B. osmotic pressure
- C. periodic group number
- D. standard potential
Explanation: That framework organizes most NEET organic logic.
Organic scope
76. Organic chemistry mainly deals with compounds of:
- A. carbon (Correct)
- B. oxygen only
- C. metals only
- D. silicon only
Explanation: Most organic compounds are carbon compounds.
Homologous series
77. Members of a homologous series differ by:
- A. $-CH_2-$ unit (Correct)
- B. an oxygen atom
- C. a nitrogen atom
- D. a proton
Explanation: Successive members differ by one methylene group.
Isomerism
78. Compounds with same molecular formula but different structures are:
- A. isomers (Correct)
- B. allotropes
- C. isotopes
- D. resonance forms
Explanation: Isomerism is central to organic chemistry.
Hybridization
79. Carbon in alkanes is generally:
- A. sp$^3$ hybridized (Correct)
- B. sp$^2$ hybridized
- C. sp hybridized
- D. unhybridized
Explanation: Single-bonded tetrahedral carbon is sp$^3$.
Inductive effect
80. Inductive effect is transmitted through:
- A. sigma bonds (Correct)
- B. pi bonds only
- C. hydrogen bonds
- D. metallic bonding
Explanation: It is a permanent electron-withdrawing or donating effect through sigma bonds.
Resonance
81. Resonance stabilizes molecules by:
- A. delocalizing electrons (Correct)
- B. increasing mass
- C. removing bonds
- D. fixing atoms in one position
Explanation: Electron delocalization lowers energy.
Carbocation
82. A carbocation is generally:
- A. electron-deficient (Correct)
- B. electron-rich
- C. neutral radical only
- D. always aromatic
Explanation: It has only six electrons around the positively charged carbon.
Stability
83. Order of carbocation stability is usually:
- A. 3$^\circ$ > 2$^\circ$ > 1$^\circ$ > methyl (Correct)
- B. methyl > 1$^\circ$ > 2$^\circ$ > 3$^\circ$
- C. 1$^\circ$ > 2$^\circ$ > 3$^\circ$
- D. all equal
Explanation: Hyperconjugation and inductive effects stabilize higher carbocations.
Carbanion
84. Order of carbanion stability is usually:
- A. methyl > 1$^\circ$ > 2$^\circ$ > 3$^\circ$ (Correct)
- B. 3$^\circ$ > 2$^\circ$ > 1$^\circ$
- C. all equal
- D. benzyl < methyl
Explanation: Alkyl groups destabilize a negatively charged carbon.
Radicals
85. Order of free-radical stability is generally:
- A. 3$^\circ$ > 2$^\circ$ > 1$^\circ$ > methyl (Correct)
- B. methyl > 1$^\circ$ > 2$^\circ$ > 3$^\circ$
- C. all equal
- D. 1$^\circ$ > 3$^\circ$
Explanation: Hyperconjugation stabilizes alkyl radicals too.
Electrophile
86. An electrophile is an electron-pair:
- A. acceptor (Correct)
- B. donor
- C. neutralizer
- D. buffer
Explanation: Electrophiles are electron-deficient species.
Nucleophile
87. A nucleophile is an electron-pair:
- A. donor (Correct)
- B. acceptor
- C. oxidiser
- D. reagent with zero electrons
Explanation: Nucleophiles are electron-rich species.
Reaction type
88. Substitution reactions involve:
- A. replacement of one atom or group by another (Correct)
- B. addition across multiple bond
- C. removal of small molecule only
- D. polymer formation always
Explanation: Substitution swaps one group for another.
Reaction type
89. Addition reactions are common in:
- A. unsaturated compounds (Correct)
- B. alkali metals
- C. noble gases
- D. saturated hydrocarbons only
Explanation: Double or triple bonds open up for addition.
Reaction type
90. Elimination reactions generally produce:
- A. multiple bonds (Correct)
- B. only single bonds
- C. salts only
- D. always alcohols
Explanation: Removal of atoms or groups creates unsaturation.
Reaction intermediate
91. The most stable resonance-stabilized carbocation among common examples is:
- A. benzyl carbocation (Correct)
- B. methyl carbocation
- C. vinyl carbocation
- D. ethyl carbocation
Explanation: Resonance disperses the positive charge over the ring.
Purification
92. Separation of liquids based on difference in boiling points is:
- A. distillation (Correct)
- B. crystallisation
- C. sublimation
- D. filtration
Explanation: This is the standard purification method for volatile liquids.
Purification
93. Steam distillation is used for compounds that are:
- A. volatile with steam and immiscible with water (Correct)
- B. ionic solids
- C. non-volatile salts
- D. always gaseous
Explanation: It allows lower-temperature distillation.
Qualitative analysis
94. The Lassaigne test is used in organic chemistry to detect:
- A. heteroatoms like N, S, and halogens (Correct)
- B. carbon only
- C. hydrogen only
- D. boiling point
Explanation: Sodium fusion converts them into ionic forms for testing.
IUPAC naming
95. Longest-chain selection is the first major step in:
- A. IUPAC nomenclature (Correct)
- B. resonance analysis
- C. electrophilic substitution
- D. steam distillation
Explanation: Naming begins by choosing the parent carbon chain.
Acid-base
96. A +I group generally:
- A. pushes electron density through sigma bonds (Correct)
- B. withdraws electron density strongly
- C. breaks all pi bonds
- D. creates aromaticity
Explanation: Electron-donating inductive groups show +I effect.
Acid-base
97. A -I group generally:
- A. withdraws electron density through sigma bonds (Correct)
- B. donates electrons to cations
- C. eliminates lone pairs
- D. always increases basicity
Explanation: Electron-withdrawing groups show -I effect.
Hyperconjugation
98. Hyperconjugation is often described as:
- A. no-bond resonance involving sigma electrons (Correct)
- B. pi bond breaking only
- C. hydrogen bonding inside molecule
- D. ionic delocalization in salts
Explanation: It helps explain stability of carbocations and alkenes.
Tautomerism
99. Keto-enol tautomerism involves migration of:
- A. proton and pi bond (Correct)
- B. carbon atom
- C. halogen atom
- D. whole alkyl group
Explanation: A proton shifts and the double bond relocates.
Organic logic
100. The cleanest way to solve many organic basics questions is to track electron flow through effects, intermediates, and:
- A. reaction type (Correct)
- B. osmotic pressure
- C. periodic group number
- D. standard potential
Explanation: That framework organizes most NEET organic logic.
Organic scope
101. Organic chemistry mainly deals with compounds of:
- A. carbon (Correct)
- B. oxygen only
- C. metals only
- D. silicon only
Explanation: Most organic compounds are carbon compounds.
Homologous series
102. Members of a homologous series differ by:
- A. $-CH_2-$ unit (Correct)
- B. an oxygen atom
- C. a nitrogen atom
- D. a proton
Explanation: Successive members differ by one methylene group.
Isomerism
103. Compounds with same molecular formula but different structures are:
- A. isomers (Correct)
- B. allotropes
- C. isotopes
- D. resonance forms
Explanation: Isomerism is central to organic chemistry.
Hybridization
104. Carbon in alkanes is generally:
- A. sp$^3$ hybridized (Correct)
- B. sp$^2$ hybridized
- C. sp hybridized
- D. unhybridized
Explanation: Single-bonded tetrahedral carbon is sp$^3$.
Inductive effect
105. Inductive effect is transmitted through:
- A. sigma bonds (Correct)
- B. pi bonds only
- C. hydrogen bonds
- D. metallic bonding
Explanation: It is a permanent electron-withdrawing or donating effect through sigma bonds.
Resonance
106. Resonance stabilizes molecules by:
- A. delocalizing electrons (Correct)
- B. increasing mass
- C. removing bonds
- D. fixing atoms in one position
Explanation: Electron delocalization lowers energy.
Carbocation
107. A carbocation is generally:
- A. electron-deficient (Correct)
- B. electron-rich
- C. neutral radical only
- D. always aromatic
Explanation: It has only six electrons around the positively charged carbon.
Stability
108. Order of carbocation stability is usually:
- A. 3$^\circ$ > 2$^\circ$ > 1$^\circ$ > methyl (Correct)
- B. methyl > 1$^\circ$ > 2$^\circ$ > 3$^\circ$
- C. 1$^\circ$ > 2$^\circ$ > 3$^\circ$
- D. all equal
Explanation: Hyperconjugation and inductive effects stabilize higher carbocations.
Carbanion
109. Order of carbanion stability is usually:
- A. methyl > 1$^\circ$ > 2$^\circ$ > 3$^\circ$ (Correct)
- B. 3$^\circ$ > 2$^\circ$ > 1$^\circ$
- C. all equal
- D. benzyl < methyl
Explanation: Alkyl groups destabilize a negatively charged carbon.
Radicals
110. Order of free-radical stability is generally:
- A. 3$^\circ$ > 2$^\circ$ > 1$^\circ$ > methyl (Correct)
- B. methyl > 1$^\circ$ > 2$^\circ$ > 3$^\circ$
- C. all equal
- D. 1$^\circ$ > 3$^\circ$
Explanation: Hyperconjugation stabilizes alkyl radicals too.
Electrophile
111. An electrophile is an electron-pair:
- A. acceptor (Correct)
- B. donor
- C. neutralizer
- D. buffer
Explanation: Electrophiles are electron-deficient species.
Nucleophile
112. A nucleophile is an electron-pair:
- A. donor (Correct)
- B. acceptor
- C. oxidiser
- D. reagent with zero electrons
Explanation: Nucleophiles are electron-rich species.
Reaction type
113. Substitution reactions involve:
- A. replacement of one atom or group by another (Correct)
- B. addition across multiple bond
- C. removal of small molecule only
- D. polymer formation always
Explanation: Substitution swaps one group for another.
Reaction type
114. Addition reactions are common in:
- A. unsaturated compounds (Correct)
- B. alkali metals
- C. noble gases
- D. saturated hydrocarbons only
Explanation: Double or triple bonds open up for addition.
Reaction type
115. Elimination reactions generally produce:
- A. multiple bonds (Correct)
- B. only single bonds
- C. salts only
- D. always alcohols
Explanation: Removal of atoms or groups creates unsaturation.
Reaction intermediate
116. The most stable resonance-stabilized carbocation among common examples is:
- A. benzyl carbocation (Correct)
- B. methyl carbocation
- C. vinyl carbocation
- D. ethyl carbocation
Explanation: Resonance disperses the positive charge over the ring.
Purification
117. Separation of liquids based on difference in boiling points is:
- A. distillation (Correct)
- B. crystallisation
- C. sublimation
- D. filtration
Explanation: This is the standard purification method for volatile liquids.
Purification
118. Steam distillation is used for compounds that are:
- A. volatile with steam and immiscible with water (Correct)
- B. ionic solids
- C. non-volatile salts
- D. always gaseous
Explanation: It allows lower-temperature distillation.
Qualitative analysis
119. The Lassaigne test is used in organic chemistry to detect:
- A. heteroatoms like N, S, and halogens (Correct)
- B. carbon only
- C. hydrogen only
- D. boiling point
Explanation: Sodium fusion converts them into ionic forms for testing.
IUPAC naming
120. Longest-chain selection is the first major step in:
- A. IUPAC nomenclature (Correct)
- B. resonance analysis
- C. electrophilic substitution
- D. steam distillation
Explanation: Naming begins by choosing the parent carbon chain.
Acid-base
121. A +I group generally:
- A. pushes electron density through sigma bonds (Correct)
- B. withdraws electron density strongly
- C. breaks all pi bonds
- D. creates aromaticity
Explanation: Electron-donating inductive groups show +I effect.
Acid-base
122. A -I group generally:
- A. withdraws electron density through sigma bonds (Correct)
- B. donates electrons to cations
- C. eliminates lone pairs
- D. always increases basicity
Explanation: Electron-withdrawing groups show -I effect.
Hyperconjugation
123. Hyperconjugation is often described as:
- A. no-bond resonance involving sigma electrons (Correct)
- B. pi bond breaking only
- C. hydrogen bonding inside molecule
- D. ionic delocalization in salts
Explanation: It helps explain stability of carbocations and alkenes.
Tautomerism
124. Keto-enol tautomerism involves migration of:
- A. proton and pi bond (Correct)
- B. carbon atom
- C. halogen atom
- D. whole alkyl group
Explanation: A proton shifts and the double bond relocates.
Organic logic
125. The cleanest way to solve many organic basics questions is to track electron flow through effects, intermediates, and:
- A. reaction type (Correct)
- B. osmotic pressure
- C. periodic group number
- D. standard potential
Explanation: That framework organizes most NEET organic logic.

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