CBSE Class 11 Chemistry Hydrocarbons MCQs Set B

Question: Which of the following can be used as the halide component for Friedel–Crafts reaction?
a) Chlorobenzene
b) Bromobenzene
c) Chloroethene
d) Isopropyl chloride
Answer: d

Question: A compound is treated with NaNH₂ to give sodium salt. Identify the compound.
a) C₂H₂
b) C₆H₆
c) C₂H₆
d) C₂H₄ 
Answer: a

Question: Which of the following alkane cannot be made in good yield by Wurtz reaction?
a) n-Hexane
b) 2, 3-Dimethylbutane
c) n-Heptane
d) n-Butane
Answer: c

Question: The most stable conformation of n-butane is
a) gauche
b) staggered
c) skew boat
d) eclipsed. 
Answer: b

Question: Which one of the following can exhibit cis-trans isomerism?
a) CH₃ – CHCl – COOH
b) H – C≡ C – Cl
c) ClCH =CHCl
d) ClCH₂ – CH₂Cl
Answer: c 

Question: Dihedral angle in staggered form of ethane is
a) 0°
b) 120°
c) 60°
d) 180°
Answer: c

Question: In Friedel-Crafts alkylation, besides AlCl₃ the other reactants are
a) C₆H₆ + CH₃Cl
b) C₆H₆ + CH₄
c) C₆H₆ + NH₃
d) C₆H₆ + CH₃COCl
Answer: a

Question: Reaction of HBr with propene in the presence of peroxide gives
a) isopropyl bromide
b) 3-bromopropane
c) allyl bromide
d) n-propyl bromide.
Answer: d

Question: The shortest C–C bond distance is found in
a) diamond
b) ethane
c) benzene
d) acetylene. 
Answer: d

Question: The correct statement regarding the comparison of staggered and eclipsed conformations of ethane, is
a) the eclipsed conformation of ethane is morestable than staggered conformation even though the eclipsed conformation has torsional strain
b) the staggered conformation of ethane is more stable than eclipsed conformation, because staggered conformation has no torsional strain
c) the staggered conformation of ethane is less stable than eclipsed conformation, because staggered conformation has torsional strain
d) the eclipsed conformation of ethane is more stable than staggered conformation, because eclipsed conformation has no torsional strain.
Answer: b

Question: Which reagent converts propene to 1-propanol?
a) H₂O, H₂SO₄
b) B₂H₆, H₂O₂, OH–
c) Hg(OAc)₂, NaBH₄/H₂O
d) Aq. KOH 
Answer: b

Question: Wet ether is not used as a solvent in Wurtz reaction, because the water present in it 
a) hydrolysis RX to ROH
b) reduces RX to RH
c) destroy the Na metal
d) reacts with R—R
Answer: c

Question: The synthesis of 3-octyne is achieved by adding a bromoalkane into a mixture of sodium amide and an alkyne. The bromoalkane and alkyne respectively are
a) BrCH₂CH₂CH₂CH₂CH₃ and CH₃CH₂C=CH
b) BrCH₂CH₂CH₃ and CH3CH₂CH₂C=CH
c) BrCH₂CH₂CH₂CH₂CH₃ and CH₃C=CH
d) BrCH₂CH₂CHH_2H3 and CH₃CH₂C = CH 
Answer: d

Question: Consider the nitration of benzene using mixed conc. H₂SO₄ and HNO₃. If a large amount of KHSO₄is added to the mixture, the rate of nitration will be
a) unchanged
b) doubled
c) faster
d) slower.
Answer: d

Question: In preparation of alkene from alcohol using Al₂O₃ which is the effective factor?
a) Porosity of Al₂O₃
b) Temperature
c) Concentration
d) Surface area of Al₂O₃ 
Answer: b

Question: The chemicals and the reaction conditions required for the preparation of ethane are 
a) C₂H₅ I, Zn -Cu, C₂H₅OH
b) CH₃Cl, Na, H₂O
c) KOOC-CH = CH-COOK electrolysis
d) CH₃CO₂Na, NaOH, CaO, Δ
Answer: a

Question: By which one of the following compounds both CH₄ and CH₃—CH₃ can be prepared in one step? 
a) CH₃I
b) CH₃OH
c) CH₃CH₂I
d) C₂H₅OH
Answer: a

Question: For synthesis of 1-butene, CH₃ Mgl should be treated with
a) propene
b) 2-chloropropene
c) allyI chloride
d) ethyl chloride 
Answer: c

Question: Butene-I may be converted to butane by reaction with
a) Zn-HCl
b) Sn-HCl 
c) Zn-Hg
d) Pd/H₂
Answer: d

Question: Pure methane can be produced by
a) Wurtz reaction
b) Kolbe's electrolytic method
c) soda lime decarboxylation
d) reduction with H₂ 
Answer: c

Question: The alkane that gives only one monochloro product on chlorination with Cl₂ in presence of diffused sunlight is
a) 2,2-dimethylbutane
b) neopentane
c) n-pentane
d) isopentane.
Answer: b

Question: Liquid hydrocarbons can be converted to a mixtureof gaseous hydrocarbons by
a) oxidation
b) cracking
c) distillation under reduced pressure
d) hydrolysis.
Answer: b

Question: Alkyl halides react with dialkyl copper reagents to give
a) alkenyl halides
b) alkanes 
c) alkyl copper halides
d) alkenes 
Answer: b

Question: The compound that will react most readily with gaseous bromine has the formula
a) C₃H₆
b) C₂H₂
c) C₄H₁₀
d) C₂H₄
Answer: a

Question: Methyl bromide is converted into ethane by heating it in ether medium with 
a) Al
b) Zn
c) Na
d) Cu
Answer: c 

Question: 2-Bromopentane is heated with potassium ethoxide in ethanol. The major product obtained is
a) trans-2-pentene
b) 1-pentene
c) 2-ethoxy pentane
d) 2-cis-pentene.
Answer: a 

Question: Reactivity of hydrogen atoms attachedto different carbon atoms in alkanes has the order
a) tertiary > primary > secondary
b) primary > secondary > tertiary
c) both tertiary > primary > secondary and primary > secondary > tertiary
d) tertiary > secondary > primary.
Answer: d

Question: In Friedel-Crafts reaction, toluene can be prepared by
a) C₆H₆ + CH₃Cl
b) C₆H₅Cl + CH₄
c) C₆H₆ + CH₂Cl₂
d) C₆H₆ + CH₃COCl 
Answer: a

Question: The reaction, CH₂= CH – CH₃ + HBr → CH₃CHBr – CH₃ is
a) electrophilic substitution
b) free radical addition
c) nucleophilic addition
d) electrophilic addition. 
Answer: d

Question: Reduction of 2-butyne with sodium in liquidammonia gives predominantly
a) cis-2-butene
b) no reaction
c) trans-2-butene
d) n-butane. 
Answer: c