Hydrocarbons MCQs [Organic Chemistry]

By: Prof. Dr. Fazal Rehman | Last updated: February 3, 2024

MCQs-based questions and answers on Hydrocarbons in organic chemistry.

Resonance energy of benzene is

1. 100 kJ/mol
2. 150 kJ/mol
3. 200 kJ/mol
4. 300 kJ/mol

Question’s Answer: 150 kJ/mol

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Alkaline KMnO₄ oxidizes acetylene to which of the following?

1. Acetic acid
2. Glyoxal
3. Oxalic acid
4. Ethylene glycol

Question’s Answer: Oxalic acid

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The hemolytic fission of hydrocarbon results in the formation of

1. Carbocation
2. Carbene
3. Carboanion
4. Free radical

Question’s Answer: Free radical

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Which reactions can be used to prepare alkane from an alkyl halide?

1. Wurtz reaction
2. Kolbe reaction
3. Fittig reaction
4. None of these

Question’s Answer: Wurtz reaction

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Which cannot be prepared by Wurtz reaction?

1. C₂H₆
2. C₄H₁₀
3. C₃H₈
4. CH₄

Question’s Answer: CH₄

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Which alkanes cannot be synthesized by Kolbe reaction of sodium salt of carboxylic acid?

1. Butane
2. Hexane
3. Ethane
4. Methane

Question’s Answer: Methane

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Cetane is a _________.

1. n-Hexane
2. n-Hexadecane
3. n-Octane
4. n-pentadecane

Question’s Answer: n-Hexadecane

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Coal is mainly a source of

1. Aromatic compounds
2. Cyclohexanes
3. Inorganic compounds
4. Aliphatic compounds

Question’s Answer: Aromatic compounds

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Which is not present in crude naphtha?

1. Gasoline
2. Petroleum ether
3. Paraffin wax
4. Hexane

Question’s Answer: Paraffin wax

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What is an Octane number of iso-octane?

1. 70
2. Zero
3. 1
4. 100

Question’s Answer: 100

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Petroleum is mainly a source of

1. Inorganic compounds
2. Aliphatic compounds
3. Aromatic compounds
4. Cyclohexanes

Question’s Answer: Aliphatic compounds

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Gasoline contains hydrocarbons in the range

1. C-5 to C-8
2. C-12 to C-15
3. C-4 to C-6
4. C-7 to C-12

Question’s Answer: C-7 to C-12

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How Successive alkanes differ?

1. CH
2. CH₂
3. CH₃
4. C₂H₅

Question’s Answer: CH₂

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Which reactions can be employed to get unsymmetrical alkanes in good yield?

1. Corey-House reaction
2. Wurtz reaction
3. Birch reaction
4. None of A, B, and C

Question’s Answer: Corey-House reaction

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Alcoholic solution of caustic potash is a specific reagent for which technique?

1. Dehydration
2. Hydration
3. Dehydrogenation
4. Dehydrohalogenation

Question’s Answer: Dehydrohalogenation

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According to ____, When an alkyl halide is treated dry ether, a symmetry alkane with Na in dry ether, a symmetry alkane is obtained.

1. Wurtz reaction
2. Grignard reaction
3. Fischer-Tropsch reaction
4. None of A, B, and C

Question’s Answer: Wurtz reaction

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The reduction of an alkyne to alkene using Lindlar’s catalyst results into

1. A mixture obtained by syn and anti-addition of hydrogen
2. Anti-addition of hydrogen atoms
3. Syn addition of hydrogen atoms
4. None of A, B, and C

Question’s Answer: Syn addition of hydrogen atoms

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The addition of HCl to 2-pentene gives which of the following?

1. 2-chloropentane3
2. 2-chloropentyne
3. -chloropentane
4. 2-chloro-2-methyl butane

Question’s Answer: 3-chloropentane

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When propyne is treated with aqueous H₂SO₄ in the presence of HgSO₄, Which is the functional isomer of the major product obtained?

1. Propanal
2. propan-2-ol
3. Propanol
4. Acetone

Question’s Answer: Acetone

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What is the relative order of stability of carbocations RC=CH₂, RCH₂ and RCH=CH RCH CH?

1. RC=CH₂ < RCH₂ > RCH== CH
2. RC CH₂ < RCH₂ < RCH=CH
3. RC=CH₂ > RCH₂ < RCH=CH
4. RC= CH₂ > RCH₂ >RCH=CH

Question’s Answer: RC= CH₂ > RCH₂ >RCH=CH

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Which is most suitable reagent to distinguish compound (III) from the rest of the compounds?

(I) CH₃C=CCH₃             (II) CH₃CH,CH,CH, ₃      (III) CH₃CH,C=CH         (IV) CH₃-CH=CH-CH₃

1. Br₂/CCI₄
2. Br₂/CH₃COOH
3. Tollen’s reagent
4. Alkaline KMnO₄

Question’s Answer: Tollen’s reagent

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__________ proved that all the six hydrogen atoms in benzene are equivalent?

1. Ladenburg
2. Kekule
3. Faraday
4. Wohler

Question’s Answer: Ladenburg

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Each of the following compound aromatic excluding which of the following?

1. Benzene
2. Cyclopentadienyl cation
3. Naphthalenec
4. Cyclopentadienyl anion

Question’s Answer: Cyclopentadienyl cation

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Sodium propionate on decarboxylation with soda-lime gives ______.

1. Propane
2. Pentane
3. Butane
4. Ethane

Question’s Answer: Ethane

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Ethyne can be prepared from a single step from

1. Calcium carbide
2. Ethylene bromide
3. Ethylidene bromide
4. All of A, B, and C

Question’s Answer: Ethylene bromide

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Chlorination of toluene in the presence of light and heat followed by treatment with aqueous NaOH gives _____________ .

1. Benzoic acid
2. p-cresol
3. 2,4-dihydroxy toluene
4. o-cresol

Question’s Answer: Benzoic acid

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Among the following statements on the nitration of aromatic compounds, the false one is

1. The rate of nitration of benzene is almost the same as that of hexadeutero- benzene
2. The rate of nitration of toluene is greater than that of benzene
3. The rate of nitration of benzene is greater than that of hexadeutero benzene
4. Nitration is an electrophilic substitution

Question’s Answer: The rate of nitration of benzene is greater than that of hexadeutero benzene

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Nitrobenzene can be prepared from benzene by using a mixture of conc. HNO3 and conc. H2SO4. In the nitrating mixture, as a/an

1. Base
2. Electrophile
3. Oxidizing agent
4. Acid

Question’s Answer: Electrophile

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The electrophile in the sulphonation of benzene is

1. SO₂
2. SO₃H
3. HSO₄
4. SO₃

Question’s Answer: SO₃

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Benzene on ozonolysis yields

1. Ethanal
2. Acetone
3. Glyoxal
4. Methanal

Question’s Answer: Glyoxal

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Chlorination of an alkane involves the attack of

1. A base
2. A free radical
3. A nucleophile
4. An electrophile

Question’s Answer: A free radical

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Complete oxidation of ethane yields

1. Ethanl
2. Ethanol
3. CO₂ and H₂O
4. Ethanoic acid

Question’s Answer: CO₂ and H₂O

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Which compounds is liquid at room temperature?

1. C₄H₁₀
2. C₁₅H₃₂
3. C₃H₈
4. C₂₀H₄₂

Question’s Answer: C₁₅H₃₂

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What is the state of hybridization of carbon in methane ?

1. sp
2. sp₃
3. sp₂
4. dsp₂

Question’s Answer: sp₃

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___________ is the formation of alkane by the action of Zn dust.

1. Wittig reaction
2. Wurtz raection
3. Kolbe reaction
4. Frankland’s reaction

Question’s Answer: Frankland’s reaction

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Which catalyst is used in the reduction of carbonyl group to -CH2

1. Zn dust
2. Ni
3. Pt
4. Z/Hg

Question’s Answer: Z/Hg

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Which of the following is the process of heating coal in the absence of air?

1. Cracking
2. Decarbonization
3. Decarboxylation
4. Isomerization

Question’s Answer: Decarbonization

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The %age of carbon is higher in ______.

1. Peat
2. Anthracite
3. Lignite
4. Bituminous

Question’s Answer: Lignite

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During distillation of coal tar, anthracene mainly present in.

1. Light oil
2. Heavy oil
3. Middle oil
4. Green oil

Question’s Answer: Green oil

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(CH3)3CMgCl on reaction with D₂O produces

1. (CD₃) CD
2. (CH₃) ₃ COD
3. (CH₃) ₃ CD
4. (CD₃) ₃ OD

Question’s Answer: (CH₃) ₃ CD

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1-Butyne on oxymercuration-demercuration would give

1. Propanol and methanol
2. Butanal
3. Butanone
4. Propanoic acid and formic acid

Question’s Answer: Butanone

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Preparation of vegetable ghee involves

1. Hydrogenation
2. Hydroxylation
3. Dehydrogenation
4. Halogenation

Question’s Answer: Hydrogenation

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Ethyl bromide reacts with Zn and HCl to form

1. Ethene
2. Propyne
3. Ethyne
4. Ethane

Question’s Answer: Ethane

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The most reactive hydrocarbon is

1. Ethene
2. Heptane
3. Acetylene
4. Ethane

Question’s Answer: Ethene

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Toluene is o/p-orienting with respect to an electrophilic substitution reaction due to

1. +1 effect of the methyl group
2. +1 as well as +R effect of the methyl group
3. Hyper conjugation between the methyl group and phenyl ring
4. +R effect of the methyl group

Question’s Answer: +1 as well as +R effect of the methyl group

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The substitution reaction in acetylene is possible by which of the following?

1. Na metal
2. Ammonical AgNO₃
3. NaNH₂
4. All of A, B, and C

Question’s Answer: Ammonical AgNO₃

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The addition of unsymmetrical reagent to an unsymmetrical alkene is in accordance with the rule of:

1. Hund’s rule
2. Pauli’s principle
3. Anti-Marknownikov’s
4. Markownikov’s rule

Question’s Answer: Markownikov’e rule

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In the Friedel-Craft acylation, the amount of AICI₃ that must be taken is

1. More than one equivalent
2. One equivalent
3. In catalytic amount
4. Amount does not matter

Question’s Answer: In catalytic amount

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Unsaturated nature of alkene can be detected by

1. Decolorisation of bromine water
2. Ozonolysis
3. Decolorisation of KMnO₄ solution
4. All of A, B, and C

Question’s Answer: All of A, B, and C

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What types of reactions are given in alkanes?

1. Addition
2. Substitution
3. Elimination
4. Polymerization

Question’s Answer: Addition

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Benzene does not undergo

1. Addition
2. Substitution
3. Elimination
4. Polymerization

Question’s Answer: Polymerization

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Which could be used as catalyst in Friedal-Craft reaction?

1. AICI₃
2. HNO₃
3. NaCl
4. BeCl₂

Question’s Answer: AICI₃

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During nitration of benzene, which is the active nitrating agent?

1. NO₃
2. NO₂
3. NO_₂⁺
4. NO

Question’s Answer: NO_₂⁺

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Which could be used as electrophile in aromatic substitution?

1. H₂SO₄
2. SO₃
3. SO₃⁺
4. HSO₄

Question’s Answer: SO₃

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The C-H bond length in benzene is

1. 1.09 Å
2. 0.99 Å
3. 1.37 Å
4. 1.12 Å

Question’s Answer: 1.09 Å

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Aromatic hydrocarbons undergo

1. Electrophilic substitution reactions
2. Electrophilic addition reaction
3. Nucleophilic addition reaction
4. None of A, B, and C

Question’s Answer: Electrophilic substitution reactions

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Benzene reacts with sunlight to form excess of chlorine in which of the following?

1. Chlorobenzene
2. Dichlorobenzene
3. Benzene hexachloride
4. Trichlorobenzene

Question’s Answer: Benzene hexachloride

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Coke is obtained by heating coal in __________ .

1. Presence of catalyst
2. Presence of air
3. Limited supply of air
4. Absence of air

Question’s Answer: Absence of air

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Which compounds has the maximum octane number?

1. 2,2,3-Trimethylpentane
2. 2,4-Dimethylhexane
3. 2,2,4-Trimethylpentane
4. n-Octane

Question’s Answer: 2,2,3-Trimethylpentane

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Aromatization of n-heptane yields

1. Benzene
2. Xylene
3. m-Xylene
4. Toluene

Question’s Answer: Toluene

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Carbonization of coal is carried out by heating coal at a temperature

1. 1500°C
2. 1000°C
3. 500°C
4. 2000°C

Question’s Answer: 1000°C

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Which compounds show geometrical isomerism?

1. Vinyl chloride
2. 1,1-Dichloroethene
3. Trichloroethene
4. 1,2-Dichloroethene

Question’s Answer: 1,2-Dichloroethene

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How many chain isomers are possible for an alkane having molecular formula C5H12?

1. 3
2. 5
3. 4
4. 2

Question’s Answer: 3

More Organic chemistry MCQs

1. Organic chemistry MCQs
2. Active Methylene Compounds MCQs
3. Alcohols and Phenols MCQs
4. Carbonyl Compounds MCQs
5. Halogenated Organic Compounds MCQs
6. Carboxylic Acids MCQs
7. Hydrocarbons MCQs
8. Nitrogen-Containing Organic Compounds MCQs
9. Polymers MCQs
10. Nomenclature of Organic Compounds MCQs
11. Organic Acids and Bases MCQs
12. Organic Spectroscopy MCQs
13. Purification and Characterization of Organic Compounds MCQs
14. Reaction Mechanism MCQs
15. Stereochemistry MCQs
16. Organic Molecules MCQs
17. CHEMISTRY MCQs From all subjects of  Chemistry

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