Class 11 – Hydrocarbons (40 MCQs)
Classification of Hydrocarbons (1–6)
- Alkanes are:
a) Saturated hydrocarbons
b) Unsaturated hydrocarbons
c) Aromatic hydrocarbons
d) Cyclic hydrocarbons - Alkenes contain:
a) Only single bonds
b) At least one double bond
c) Triple bonds
d) Benzene rings - Alkynes contain:
a) Single bonds
b) At least one double bond
c) At least one triple bond
d) Aromatic rings - Aromatic hydrocarbons contain:
a) Only single bonds
b) Only double bonds
c) Conjugated pi electrons in a ring
d) Triple bonds - Methane (CH₄) belongs to:
a) Alkane
b) Alkene
c) Alkyne
d) Aromatic - C₂H₂ belongs to:
a) Alkane
b) Alkene
c) Alkyne
d) Aromatic
Nomenclature of Hydrocarbons (7–11)
- IUPAC name of CH₃–CH₂–CH₃ is:
a) Propane
b) Propene
c) Propyne
d) Methane - Parent chain selection in alkanes is based on:
a) Shortest chain
b) Longest chain
c) Number of hydrogens
d) Number of functional groups - Numbering of the chain is done to:
a) Give substituents lowest locants
b) Give parent chain highest locants
c) Maximize double bonds
d) Maximize hydrogens - CH₃–CH=CH₂ is named as:
a) Propane
b) Propene
c) Propanol
d) Propanone - Benzene with –NO₂ substituent is named as:
a) Nitrobenzene
b) Aminobenzene
c) Chlorobenzene
d) Phenol
Properties and Reactions of Alkanes (12–18)
- Alkanes are generally:
a) Reactive
b) Unreactive
c) Ionic
d) Acids - Combustion of methane produces:
a) CO + H₂O
b) CO₂ + H₂O
c) CH₃OH
d) CO₂ only - Halogenation of alkanes requires:
a) Heat or light
b) Acid
c) Base
d) Catalyst - Which is a reaction of alkanes?
a) Substitution
b) Addition
c) Elimination
d) Oxidation - Methane reacts with Cl₂ to form:
a) CH₃Cl
b) C₂H₆
c) C₂H₄
d) CO₂ - Alkanes are:
a) Polar
b) Non-polar
c) Ionic
d) Amphoteric - Which is an example of cycloalkane?
a) C₆H₁₂
b) C₂H₄
c) C₂H₂
d) C₆H₆
Properties and Reactions of Alkenes (19–25)
- Alkenes undergo:
a) Addition reactions
b) Substitution reactions
c) Combustion only
d) None - CH₂=CH₂ + Br₂ → CH₂Br–CH₂Br is:
a) Substitution
b) Addition
c) Elimination
d) Oxidation - Markovnikov’s rule applies to:
a) Alkane reactions
b) Alkene addition reactions
c) Alkyne reactions
d) Aromatic reactions - Polymerization of ethene forms:
a) Polyethylene
b) Polypropylene
c) Polystyrene
d) Nylon - Hydrogenation of alkenes produces:
a) Alkynes
b) Alkanes
c) Aromatic compounds
d) Alcohols - Acid-catalyzed hydration of ethene produces:
a) Ethanol
b) Ethane
c) Acetylene
d) Methanol - Oxidation of alkenes with KMnO₄ gives:
a) Alcohols or diols
b) Alkynes
c) Alkanes
d) Aromatic compounds
Properties and Reactions of Alkynes (26–30)
- Alkynes are:
a) Saturated
b) Unsaturated
c) Aromatic
d) Non-reactive - C₂H₂ + H₂ → C₂H₄ is:
a) Addition reaction
b) Substitution reaction
c) Elimination reaction
d) Oxidation - Alkynes undergo:
a) Addition reactions
b) Substitution reactions
c) Only combustion
d) None - Terminal alkyne contains:
a) –C≡C–H
b) –CH=CH–
c) –CH₃
d) Aromatic ring - Acidity of terminal alkyne is due to:
a) sp³ hybridization
b) sp² hybridization
c) sp hybridization
d) Aromaticity
Aromatic Hydrocarbons (31–37)
- Benzene is:
a) Saturated
b) Unsaturated
c) Aromatic
d) Aliphatic - Benzene resists:
a) Addition reactions
b) Substitution reactions
c) Combustion
d) Oxidation - Nitration of benzene uses:
a) H₂SO₄ + HNO₃
b) Br₂ + FeBr₃
c) NaOH + HCl
d) KMnO₄ - Benzene undergoes which type of reaction predominantly?
a) Electrophilic substitution
b) Addition
c) Elimination
d) Combustion only - Kekulé’s model explains:
a) Resonance in benzene
b) Addition reactions
c) Polymerization
d) Alkyne reactions - Toluene is:
a) CH₄
b) C₆H₅CH₃
c) C₂H₂
d) C₂H₄ - Phenol reacts with bromine to give:
a) Tribromophenol
b) Bromobenzene only
c) No reaction
d) Benzene
Conceptual / Application Questions (38–40)
- Saturated hydrocarbons have:
a) Double bonds
b) Triple bonds
c) Only single bonds
d) Aromatic rings - Unsaturated hydrocarbons react with bromine water to:
a) Decolorize it
b) Retain color
c) Form carboxylic acid
d) Form ketone - The general formula of alkanes is:
a) CₙH₂ₙ
b) CₙH₂ₙ₊₂
c) CₙH₂ₙ₋₂
d) CₙHₙ
Answer Key – Class 11 Chemistry: Hydrocarbons (40 MCQs)
Classification of Hydrocarbons (1–6)
- a) Saturated hydrocarbons – Alkanes contain only single bonds.
- b) At least one double bond – Alkenes are unsaturated with one or more double bonds.
- c) At least one triple bond – Alkynes have a carbon–carbon triple bond.
- c) Conjugated pi electrons in a ring – Aromatic hydrocarbons have delocalized π electrons.
- a) Alkane – Methane is a saturated hydrocarbon.
- c) Alkyne – C₂H₂ (acetylene) has a triple bond.
Nomenclature of Hydrocarbons (7–11)
- a) Propane – CH₃–CH₂–CH₃ is propane.
- b) Longest chain – Parent chain is chosen as the longest continuous carbon chain.
- a) Give substituents lowest locants – Numbering is done to assign lowest numbers to substituents.
- b) Propene – CH₂=CH–CH₃ contains a double bond.
- a) Nitrobenzene – Benzene with –NO₂ group is nitrobenzene.
Properties and Reactions of Alkanes (12–18)
- b) Unreactive – Alkanes are relatively inert due to strong C–C and C–H bonds.
- b) CO₂ + H₂O – Complete combustion produces carbon dioxide and water.
- a) Heat or light – Halogenation requires initiation energy.
- a) Substitution – Alkanes primarily undergo substitution reactions.
- a) CH₃Cl – Chlorination of methane gives methyl chloride.
- b) Non-polar – Alkanes are non-polar, insoluble in water.
- a) C₆H₁₂ – Cycloalkane example.
Properties and Reactions of Alkenes (19–25)
- a) Addition reactions – Alkenes react by addition across C=C.
- b) Addition – Bromine adds across double bond.
- b) Alkene addition reactions – Markovnikov’s rule applies to electrophilic addition.
- a) Polyethylene – Polymer of ethene.
- b) Alkanes – Hydrogenation converts alkenes to alkanes.
- a) Ethanol – Acid-catalyzed hydration adds H and OH.
- a) Alcohols or diols – Oxidation of alkenes can form diols.
Properties and Reactions of Alkynes (26–30)
- b) Unsaturated – Alkynes contain triple bonds, making them unsaturated.
- a) Addition reaction – Hydrogen adds to C≡C to form C=C.
- a) Addition reactions – Alkynes undergo addition due to unsaturation.
- a) –C≡C–H – Terminal alkyne has a hydrogen on the triple-bonded carbon.
- c) sp hybridization – Terminal alkyne acidity arises from sp hybridized carbon.
Aromatic Hydrocarbons (31–37)
- c) Aromatic – Benzene is an aromatic hydrocarbon.
- a) Addition reactions – Benzene resists addition due to resonance stability.
- a) H₂SO₄ + HNO₃ – Nitration requires concentrated acids.
- a) Electrophilic substitution – Aromatic rings undergo substitution, not addition.
- a) Resonance in benzene – Kekulé proposed delocalized structure.
- b) C₆H₅CH₃ – Toluene formula.
- a) Tribromophenol – Phenol reacts with bromine to give 2,4,6-tribromophenol.
Conceptual / Application Questions (38–40)
- c) Only single bonds – Saturated hydrocarbons have only single bonds.
- a) Decolorize it – Unsaturated hydrocarbons react with Br₂ water, removing the color.
- b) CₙH₂ₙ₊₂ – General formula of alkanes.
Disclaimer:
All MCQs on this page are created for educational purposes only. They are intended for practice and NEET/Class 11 Chemistry preparation and do not guarantee any specific exam results.