Q.1 Which of the following is an aromatic hydrocarbon?
Methane
Ethene
Benzene
Butane
Explanation - Benzene is an aromatic hydrocarbon with a planar ring structure and delocalized π electrons.
Correct answer is: Benzene
Q.2 What type of hybridization is present in ethyne (C2H2)?
sp
sp2
sp3
sp3d
Explanation - In ethyne, each carbon is bonded to two atoms with a triple bond, giving sp hybridization.
Correct answer is: sp
Q.3 Which of the following is an example of an alkyne?
Ethane
Ethene
Ethyne
Propane
Explanation - Ethyne (C2H2) contains a triple bond between carbons, classifying it as an alkyne.
Correct answer is: Ethyne
Q.4 The general formula of an alkane is:
CnH2n+2
CnH2n
CnH2n-2
CnHn
Explanation - Alkanes are saturated hydrocarbons with single bonds, following the formula CnH2n+2.
Correct answer is: CnH2n+2
Q.5 Which reaction is typical of alkanes?
Electrophilic addition
Substitution
Electrophilic substitution
Condensation
Explanation - Alkanes are relatively unreactive but undergo substitution reactions, such as halogenation.
Correct answer is: Substitution
Q.6 Which of the following hydrocarbons exhibits cis-trans isomerism?
Ethane
Ethene
Ethyne
Methane
Explanation - Ethene has a double bond; restricted rotation allows cis-trans isomerism.
Correct answer is: Ethene
Q.7 The product of complete combustion of hydrocarbons is:
CO2 and H2O
CO and H2O
C and H2O
CH4
Explanation - Complete combustion of hydrocarbons produces carbon dioxide and water.
Correct answer is: CO2 and H2O
Q.8 Which of the following is an example of a branched-chain alkane?
Butane
Isobutane
Pentane
Hexane
Explanation - Isobutane is a branched isomer of butane with three carbons in the main chain and one methyl branch.
Correct answer is: Isobutane
Q.9 Markovnikov’s rule is applied in which type of reaction?
Addition of HX to alkenes
Combustion of alkanes
Substitution of alkanes
Elimination of alkanes
Explanation - Markovnikov’s rule predicts that in HX addition, the H attaches to the carbon with more hydrogens.
Correct answer is: Addition of HX to alkenes
Q.10 Which of the following hydrocarbons is most reactive?
Methane
Ethene
Benzene
Ethane
Explanation - Alkenes like ethene are more reactive than alkanes due to the presence of a double bond.
Correct answer is: Ethene
Q.11 What type of isomerism is shown by C4H10?
Structural isomerism
Geometrical isomerism
Optical isomerism
Tautomerism
Explanation - C4H10 has two structural isomers: n-butane and isobutane.
Correct answer is: Structural isomerism
Q.12 Which reagent is used in the halogenation of alkanes?
Br2/UV light
H2/Pt
KMnO4
NaOH
Explanation - Halogenation of alkanes requires bromine and UV light to initiate a free radical reaction.
Correct answer is: Br2/UV light
Q.13 Which compound is an example of a cyclic alkane?
Cyclopentane
Propene
Benzene
Methane
Explanation - Cyclopentane is a cyclic saturated hydrocarbon (cycloalkane).
Correct answer is: Cyclopentane
Q.14 Which reaction is characteristic of alkenes?
Addition reaction
Substitution reaction
Free radical halogenation
Combustion
Explanation - Alkenes undergo addition reactions due to the presence of a double bond.
Correct answer is: Addition reaction
Q.15 Which of the following hydrocarbons is unsaturated?
Ethane
Butane
Ethene
Methane
Explanation - Unsaturated hydrocarbons contain double or triple bonds; ethene has a double bond.
Correct answer is: Ethene
Q.16 What is the IUPAC name of CH3-CH=CH2?
Propene
Propyne
Propane
Propanol
Explanation - CH3-CH=CH2 is an alkene with three carbon atoms; its IUPAC name is propene.
Correct answer is: Propene
Q.17 Which catalyst is used in the hydrogenation of alkenes?
Ni or Pt
Al2O3
MnO2
FeCl3
Explanation - Hydrogenation of alkenes requires a metal catalyst such as Ni or Pt.
Correct answer is: Ni or Pt
Q.18 Which hydrocarbon reacts with hot concentrated KMnO4 to give a diol?
Alkane
Alkene
Alkyne
Aromatic
Explanation - Alkenes undergo oxidation with hot KMnO4 to form vicinal diols.
Correct answer is: Alkene
Q.19 The general formula for an alkyne is:
CnH2n-2
CnH2n+2
CnH2n
CnHn
Explanation - Alkynes are hydrocarbons with triple bonds, following the formula CnH2n-2.
Correct answer is: CnH2n-2
Q.20 Which of the following is a linear alkyne?
Propyne
Cyclopentyne
Butadiene
Benzene
Explanation - Propyne (CH3-C≡CH) is a straight-chain alkyne.
Correct answer is: Propyne
Q.21 Which of the following hydrocarbons undergoes aromatic substitution?
Benzene
Ethene
Methane
Ethyne
Explanation - Benzene undergoes electrophilic aromatic substitution due to its stable aromatic ring.
Correct answer is: Benzene
Q.22 Which of these is an isomer of C5H12?
Pentane
Pentene
Cyclopentane
Cyclopentene
Explanation - C5H12 has three isomers: n-pentane, isopentane, and neopentane.
Correct answer is: Pentane
Q.23 Which compound shows chain isomerism?
Butane
Cyclobutane
Ethene
Propyne
Explanation - Chain isomerism occurs when compounds have the same molecular formula but different chain arrangements, e.g., n-butane and isobutane.
Correct answer is: Butane
Q.24 The simplest alkyne is:
Methyne
Ethyne
Propyne
Methane
Explanation - Ethyne (C2H2) is the simplest alkyne with a carbon-carbon triple bond.
Correct answer is: Ethyne
Q.25 Which hydrocarbon is most likely to undergo addition reaction with bromine?
Alkane
Alkene
Aromatic
Cycloalkane
Explanation - Alkenes contain a double bond that reacts with bromine in addition reactions.
Correct answer is: Alkene