JEE Chemistry Hydrocarbons MCQs Set A

Question: Which of the following fuel cause the least pollution ?

• a) LPG
• b) CNG
• c) Petrol
• d) Kerosene

Answer: LPG

Question: LPG mainly contains

• a) butane
• b) ethane
• c) ethyne
• d) methane

Answer: butane

Question: Natural gas is a mixture of

• a) CH₄ + C₂H₆ + C₃H₈
• b) CO + H₂ + CH₄
• c) CO + H₂
• d) None of these

Answer: CH₄ + C₂H₆ + C₃H₈

Question: Which of the following gas is find in coal mines and marshy places?

• a) Methane
• b) Benzene
• c) Ethane
• d) Propane

Answer: Methane

Question: Which of the following represents the correct general formula of alkanes ?

• a) C_nH2_{n + 2}
• b) C_nH_n
• c) C_nH_2n
• d) C_nH_{2n – 2}

Answer: C_nH_{2n + 2}

Question: Two adjacent members of a homologous series have

• a) All the above
• b) same general method of preparation
• c) a different of 14 amu in molecular mass
• d) a difference of CH₂ in their structure

Answer: All the above

Question: Methane, ethane and propane are said to form a homologous series because all are

• a) differ from each other by a CH₂ group
• b) aliphatic compounds
• c) saturated compounds
• d) hydrocarbons

Answer: differ from each other by a CH₂ group

Question: Which of the following does not belong to the same homologous series?

• a) C₄H₈
• b) C₂H₆
• c) CH₄
• d) C₃H₈

Answer: C₄H₈

Question:  In which of the following compounds only primary carbon atoms are present?

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question:

• a) 3-ethyl-5-methylheptane
• b) 5-ethyl-3-methylheptane
• c) 3,5-diethylhexane
• d) 1,1-diethyl-3-methylpentane

Answer: 3-ethyl-5-methylheptane

Question: The number of chain isomers possible for the hydrocarbon C₅H₁₂ is

• a) 3
• b) 1
• c) 2
• d) 4

Answer: 3

Question: The number of primary, secondary and tertiary carbons in 3, 4-dimethylheptane are respectively

• a) 4, 3 and 2
• b) 4, 2 and 3
• c) 2, 3 and 4
• d) 3, 4 and 2

Answer: 4, 3 and 2

Question:

• a) 4-ethyl-3-methyl octane
• b) 2, 3-diethyl heptane
• c) 5-ethyl-6-methyl octane
• d) 3-methyl-4-ethyl octane

Answer: 4-ethyl-3-methyl octane

Question: Which of the following statements is false for isopentane

• a) It has a carbon which is not bonded to hydrogen
• b) It has one CH group
• c) It has one CH₂ group
• d) It has three CH₃ groups

Answer: It has a carbon which is not bonded to hydrogen

Question: Molecular formula of which of the following alkane can exist in more than one structure ?

• a) C₄H₁₀
• b) C₂H₆
• c) CH₄
• d) None of these

Answer: C₄H₁₀

Question: How many isomers are possible for the C₅H₁₂ ?

• a) 3
• b) 5
• c) 2
• d) 4

Answer: 3

Question: The number of 4° carbon atoms in 2,2,4,4-tetramethyl pentane is –

• a) 2
• b) 4
• c) 1
• d) 3

Answer: 2

Question: Which one of the following cannot be prepared by Wurtz reaction ?

• a) CH₄
• b) C₃H₈
• c) C₂H₆
• d) C₄H₁₀

Answer: CH₄

Question:

• a) Wurtz reaction
• b) Aldol condensation
• c) Levit reaction
• d) Perkin’s reaction

Answer: Wurtz reaction

Question: Pure methane can be produced by

• a) Soda-lime decarboxylation
• b) Reduction with H₂
• c) Kolbe’s electrolytic method
• d) Wurtz reaction

Answer: Soda-lime decarboxylation

More Questions.........................................

Question: Sodium salts of carboxylic acids on heating with soda lime give alkanes containing _______ than the carboxylic acid.

• a) one carbon less
• b) one carbon more
• c) two carbon less
• d) None of these

Answer: one carbon less

Question: Which one of the following has the least boiling point?

• a) 2, 2– dimethylpropane
• b) n-butane
• c) n-pentane
• d) 2-methylpropane

Answer: 2, 2– dimethylpropane

Question: Which one of the following has highest boiling point?

• a) n-Octane
• b) Iso-octan
• c) 2,2 dimethyl pentane
• d) All have equal values

Answer: n-Octane

Question: Which of the following reactions of methane is incomplete combustion ?

• a)

  

• b)

  

• c)

  

• d) None of these

Answer:

Question: Which one of the following gives only one monochloro derivative?

• a) neo-pentane
• b) 2-methylpentane
• c) n-hexane
• d) 2, 3-dimethylpentane

Answer: neo-pentane

Question: Photochemical halogenation of alkane is an example of

• a) free radical substitution
• b) nucleophilic substitution
• c) electrophilic addition
• d) electrophilic substitution

Answer: free radical substitution

Question: 2-Methylbutane on reacting with bromine in the presence of sunlight gives mainly

• a) 2-bromo-2-methylbutane
• b) 2-bromo-3-methylbutane
• c) 1-bromo-3-methylbutane
• d) 1-bromo-2-methylbutane

Answer: 2-bromo-2-methylbutane

Question:  Complete combustion of CH₄ gives

• a)

  

• b)

  

• c)

  

• d) None of these

Answer:

Question: Aromatisation of n-hexane gives

• a) benzene
• b) toluene
• c) cyclohexane
• d) cycloheptane

Answer: benzene

Question: Liquid hydrocarbons can be converted to a mixture of gaseous hydrocarbons by

• a) cracking
• b) oxidation
• c) distillation under reduced pressure
• d) hydrolysis

Answer: cracking

Question: n-Hexane isomerises in presence of anhydrous aluminium chloride and hydrogen chloride gas to give

• a) Both
• b) 2-Methyl pentane
• c) 3-Methyl pentane
• d) None of these

Answer: Both

Question:  Which of the following represents the correct reaction ?

• a)

  

• b)

  

• c)

  

• d) None of these

Answer:

Question: How many conformations are possible for ethane ?

• a) infinite
• b) 2
• c) 3
• d) one

Answer: infinite

Question: Spatial arrangements of atoms which can be converted into one another by rotation around a C–C single bond are called

• a) Conformers
• b) Tautomers
• c) Stereoisomers
• d) Optical isomers

Answer: Conformers

Question:  General formula of alkenes and alkyl radicals are respectively:

• a)

  

• b)

  

• c)

  

• d) None of these

Answer:

Question: The restricted rotation about carbon-carbon double bond in 2- butene is due to

• a) sideways overlap of two p-orbitals
• b) overlap of one p-and one sp²-hybridized orbitals
• c) overlap of two sp²-hybridized orbitals
• d) overlap of one s- and one sp²-hybridized orbitals

Answer: sideways overlap of two p-orbitals

Question: Bond angle in alkenes is equal to

• a) 120°
• b) 180°
• c) 109°28'
• d) 60°

Answer: 120°

Question: The molecular formula of a compound in which double bond is present between C & C

• a) C_nH_2n
• b) C_nH_{2n + 2}
• c) C_nH_2n–2
• d) None of these

Answer: C_nH_2n

Question:

• a) 5-chlorohex-2-ene
• b) 4-chloropent-1-ene
• c) 5-chloroheptene
• d) 5-chloropent-3-ene

Answer: 5-chlorohex-2-ene

Question: Reaction of hydrogen bromide with propene in the absence of peroxide is a/an

• a) electrophilic addition
• b) electrophilic substitution
• c) nucleophilic addition
• d) free radical addition

Answer: electrophilic addition

Question:

• a) 3–Ethyl–2–hexene
• b) 3–Propyl–3–hexene
• c) 3–Propyl–3–hexene
• d) 4–Ethyl–4–hexene

Answer: 3–Ethyl–2–hexene

Question: Which of the following represents the correct IUPAC name of the compound

CH₂ = CH – CH₂ Cl?

• a) 3- chloro-1- propene
• b) Allyl chloride
• c) Vinyl chloride
• d) None of these

Answer: 3- chloro-1- propene

Question:

• a) 2, 3- dibromo -1, 4- dichlorobutene-2
• b) 1, 4- dichloro-2, 3- dibromobutene-2
• c) Dichlorodibromobutene
• d) None of these

Answer: 2, 3- dibromo -1, 4- dichlorobutene-2

Question:

• a) 4-Hydroxy-2-methylpent-2-en-1-al
• b) 2-Hydroxy-4-methylpent-3-en-5-al
• c) 2-Hydroxy-3-methylpent-2-en-5-al
• d) 4-Hydroxy-1-methylpentanal

Answer: 4-Hydroxy-2-methylpent-2-en-1-al

Question: The alkene that exhibits geometrical isomerism is

• a) 2-butene
• b) propene
• c) 2- methyl propene
• d) 2- methyl -2- butene

Answer: 2-butene

Question: Which one of the following exhibits geometrical isomerism?

• a) Both
• b) 1, 2-dibromopropene
• c) 2, 3-dibromobut-2-ene
• d) None of these

Answer: Both

Question: The compounds CH₃CH == CHCH₃ and CH₃CH₂CH == CH₂

• a) are position isomers
• b) are tautomers
• c) exist together in dynamic equilibrium
• d) None of these

Answer: are position isomers

Question: The total number of isomers for C₄H₈ is

• a) 6
• b) 8
• c) 5
• d) 7

Answer: 6

Question: Consider the following statements : A hydrocarbon of molecular formula C₅H₁₀ is a

I. monosubstituted alkene
II. disubstituted alkene
III. trisubstituted alkene
Which of the following statement(s) is(are) correct?

• a) I, II and III
• b) I and II
• c) II and III
• d) I and III

Answer: I, II and III

Question: Geometrical isomerism is not shown by

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question: Hex-2-ene and 2-methylpent-2-ene exhibit

• a) chain isomerism
• b) geometrical isomerism
• c) position isomerism
• d) optical isomerism

Answer: chain isomerism

Question:  Ethyl bromide gives ethylene when reacted with

• a) alcoholic KOH
• b) dilute H₂SO₄
• c) ethyl alcohol
• d) aqueous KOH

Answer: alcoholic KOH

Question: By which reaction ethene is obtained from ethyne

• a) hydrogenation
• b) oxidation
• c) polymerisation
• d) dehydrogenation

Answer: hydrogenation

Question: Ethyl alcohol is heated with conc. H₂SO₄ . The product formed is

• a) C₂H₄
• b) C₂H₂
• c) C₂H₆
• d) None of these

Answer: C₂H₄

Question: Alcoholic solution of KOH is used for

• a) Dehydrohalogenation
• b) Dehalogenation
• c) Dehydrogenation
• d) Dehydration

Answer: Dehydrohalogenation

Question:  Paraffins are soluble in

• a) Benzene
• b) Sea water
• c) Distilled water
• d) Methanol

Answer: Benzene

Question: When hydrochloric acid gas is treated with propene in presence of benzoyl peroxide, it gives

• a) 2-Chloropropane
• b) No reaction
• c) Allyl chloride
• d) n-Propyl chloride

Answer: 2-Chloropropane

Question: "The addition of unsymmetrical reagents to unsymmetrical alkenes occurs in such a way that the negative part of the addendum goes to that carbon atom of the double bond which carries lesser number of hydrogen atoms" is called by

• a) Markownikoff's rule
• b) Anti-Saytzeff rule
• c) Saytzeff rule
• d) Kharasch effect

Answer: Markownikoff's rule

Question: When one mole of an alkene on ozonolysis produces 2 moles of propanone, the alkene is

• a) 2, 3-dimethyl-2-butene
• b) 2, 3-dimethyl-2-pentene
• c) 2, 3-dimethyl-1-butene
• d) 3-methyl-1-butene

Answer: 2, 3-dimethyl-2-butene

Question: The major product formed when 2-bromobutane is treated with alcoholic KOH is

• a) Trans-2-butene
• b) 1-Butene
• c) 2-Butanol
• d) 1-Butanol

Answer: Trans-2-butene

Question:

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question: Reaction of HBr with propene in the presence of peroxide give

• a) n-propyl bromide
• b) 3-bromo propane
• c) isopropyl bromide
• d) allyl bromide

Answer: n-propyl bromide

Question:

• a)

  

• b)

  

• c)

  

• d) None of these

Answer:

Question: Butene-1 may be converted to butane by reaction with

• a) Pd/H₂
• b) Sn – HCl
• c) Zn – Hg
• d) Zn – HCl

Answer: Pd/H₂

Question: Alkenes usually show which type of reaction

• a) addition
• b) elimination
• c) substitution
• d) superposition

Answer: addition

Question:  A reagent used to test unsaturation in alkene is

• a) solution of Br₂ in CCl₄
• b) conc. H₂SO₄
• c) ammonical AgNO₃
• d) ammonical Cu₂Cl₂

Answer: solution of Br₂ in CCl₄

Question:

• a) KMnO⁴/OH^–
• b) Conc. HCl +Anhy.ZnCl₂
• c) C₂H₅ONa
• d) None of these

Answer:  KMnO⁴/OH^–

Question: Polythene is a resin obtained by polymerisation of

• a) Ethylene
• b) Ethyne
• c) Methane
• d) None of these

Answer: Ethylene

Question: Ethyl hydrogen sulphate is obtained by reaction of H₂SO₄ on

• a) Ethylene
• b) Ethyl chloride
• c) Ethane
• d) Ethane

Answer: Ethylene

Question: The negative part of an addendum adds on to the carbon atom joined to the least number of hydrogen atoms. This statement is called

• a) Markownikoff’s rule
• b) Thiele’s theory
• c) Peroxide effect
• d) Baeyer’s strain theory

Answer: Markownikoff’s rule

Question:  Which of the following compounds does not follow Markownikoff’s law ?

• a) CH₃CH = CHCH₃
• b) CH₃CH = CH₂
• c) CH₂CHCl
• d) None of these

Answer: CH₃CH = CHCH₃

Question:

• a) CH₃CHO
• b) CH₃COCH₃
• c) CH₃CH₂CHO
• d) None f these

Answer: CH₃CHO

Question: One mole of a symmetrical alkene on ozonolysis gives two moles of an aldehyde having a molecular mass of 44 u. The alkene is

• a) 2-butene
• b) propene
• c) 1-butene
• d) ethene

Answer: 2-butene

Question: The alkene that will give the same product with HBr in the absence as well as in the presence of peroxide is

• a) 2-butene
• b) propene
• c) 1-butene
• d) 1-hexene

Answer: 2-butene

Question: Ethylene reacts with alkaline KMnO₄ to form

• a) Glycol
• b) HCHO
• c) Oxalic acid
• d) Ethyl alcohol

Answer: Glycol

Question: Ethene when treated with Br₂ in the presence of CCl₄ which compound is formed

• a) 1-bromo-2-chloroethane
• b) 1, 2-dibromoethane
• c) 1, 1, 1-tribromoethane
• d) None of these

Answer: 1-bromo-2-chloroethane

Question:

• a)

  

• b)

  

• c)

  

• d) None of these

Answer:

Question: The test for unsaturation is confirmed by the decolourisation of which of the following

• a) Bromine water
• b) Iodine water
• c) CuSO₄ solution
• d) All of these

Answer: Bromine water

Question: Isopropyl alcohol is obtained by reacting which of the following alkenes with conc. H₂SO₄ and H₂O

• a) Propylene
• b) Isoprene
• c) Ethylene
• d) 2-methyl propene

Answer: Propylene

Question: In the presence of peroxide, hydrogen chloride and hydrogen iodide do not give anti-Markownikov’s addition to alkenes because

• a) One of the steps is endothermic in both the cases
• b) All the steps are exothermic in both the cases
• c) One is oxidising and the other is reducing
• d) None of these

Answer: One of the steps is endothermic in both the cases