CBSE Class 12 Chemistry Haloalkanes and Haloarenes MCQs

Question : Among the following which one can have a meso form?

(a) CH₃CH(OH)CH(Cl)C₂H₅
(b) CH₃CH(OH)CH(OH)CH₃
(c) C₂H₅CH(OH)CH(OH)CH₃
(d) HOCH₂CH(Cl)CH₃

Answer : B 

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

(a) CH₃CH₂CH₂Cl
(b) CH₃CH₂CH₂CH₂Cl
(c) CH₃CH(CH₃ )CH₂Cl
(d) (CH₃)₃CCl

Answer : B 

Question : In the following sequence of the reations, what is D?

(a) Primary amine
(b) An amide
(c) Phenyl isocyanate
(d) A chain lengthened hydrocarbon

Answer : C 

Question : Which of the following is optically inactive?

Answer : C 

Question : The pesticide DDT slowly changes to

(a) CCl_3-CHO and chlorobenzene
(b) p, p'-Dichlorodiphenylethene
(c) p, p'-Dichlorodiphenyldichloroethane
(d) p, p'-Dichlorodiphenyldichloroethene

Answer : D 

Question : Rectified spirit is a mixture of

(a) 95% ethyl alcohol + 5% water
(b) 94% ethyl alcohol + 4.53 water
(c) 94.4% ethyl alcohol + 5.43% water
(d) 95.87% ethyl alcohol + 4.13% water

Answer : D  

Question : Which of the following is an example of SN₂ reaction? 

Answer : A 

Question : Which of the following pairs is/are correctly matched?

(a) Only I       

(b) I and II

(c) III and IV  

(d) I, II, III and IV

Answer : B 

Question : The solution of a chemical compound reacts with AgNO₃ solution to form a white preciptate of Y which dissolves in NH₄OH to give a complex Z. When Z is treated with dilute HNO₃, Y reappears. The chemical compound X can be

(a) NaCl 

(b) CH₃Cl

(c) NaBr 

(d) NaI

Answer : A

Question : The synthesis of alkyl fluorides is best accomplished by

(a) Finkelstein reaction
(b) Swarts reaction
(c) Free radical fluorination
(d) Sandmeyer's reaction

Answer : B

Question : Which of the following is a primary halide?

(a) Isopropyl iodide

(b) Secondary butyl iodide

(c) Tertiary butyl bromide

(d) Neohexyl chloride

Answer : D

Question : When two halogen atoms are attached to same carbon atom then it is :

(a) vic-dihalide

(b) gem-dihalide

(c) α, ω -halide

(d) α, β -halide

Answer : B

Question : Gem-dibromide is

(a) CH₃CH(Br)CH₂(Br)

(b) CH₃CBr₂CH₃

(c) CH₂(Br)CH₂CH₂

(d) CH₂BrCH₂Br

Answer : B

Question : How many structural isomers are possible for a compound with molecular formula C₃H₇Cl ?

(a) 2

(b) 5

(c) 7

(d) 9

Answer : A

Question : The compound which contains all the four 1°, 2°, 3° and 4° carbon atoms is

(a) 2, 3-dimethyl pentane

(b) 3-chloro-2, 3-dimethylpentane

(c) 2, 3, 4-trimethylpentane

(d) 3, 3-dimethylpentane

Answer : B

Question : IUPAC name of (CH₃)₃CCl

(a) 3-Chlorobutane

(b) 2-Chloro-2-methylpropane

(c) t-butyl chloride

(d) n-butyl chloride

Answer : B

Question : IUPAC name of CH₃CH₂C(Br) = CH—Cl is

(a) 2-bromo-1-chloro butene

(b) 1-chloro-2-bromo butene

(c) 3-chloro-2-bromo butene

(d) None of the above

Answer : A

Question : The IUPAC name of CH₂ = CH - CH₂Cl is

(a) Allyl chloride

(b) 1-chloro-3-propene

(c) Vinyl chloride

(d) 3-chloro-1-propene

Answer : D

Question : Which of the following halide is 2° ?

(a) Isopropyl chloride

(b) Isobutyl chloride

(c) n-propyl chloride

(d) n-butyl chloride

Answer : A

Question : Benzene hexachloride is

(a) 1, 2, 3, 4, 5, 6 - hexachlorocyclohexane

(b) 1, 1, 1, 6, 6, 6 - hexachlorocyclohexane

(c) 1, 6 - phenyl - 1, 6 - chlorohexane

(d) 1, 1 - phenyl - 6, 6 -chlorohexane

Answer : A

Question : Phosgene is a common name for

(a) phosphoryl chloride

(b) thionyl chloride

(c) carbon dioxide and phosphine

(d) carbonyl chloride

Answer : D

Question : C – X bond is strongest in

(a) CH₃Cl

(b) CH₃Br

(c) CH₃F

(d) CH₃I

Answer : C

Question : Which of the following will have the maximum dipole moment?

(a) CH₃F

(b) CH₃Cl

(c) CH₃Br

(d) CH₃I

Answer : B

Question : The decreasing order of boiling points of alkyl halides is

(a) RF > RCl > RBr > RI

(b) RBr > RCl > RI > RF

(c) RI > RBr > RCl > RF

(d) RCl > RF > RI > RBr

Answer : C

Question : Halogenation of alkanes is

(a) a reductive process

(b) an oxidative process

(c) an isothermal process

d) an endothermal process

Answer : B

Question : Ethylene dichloride can be prepared by adding HCl to

(a) Ethane

(b) Ethylene

(c) Acetylene

(d) Ethylene glycol

Answer : D

Question : In which of the following conversions, phosphorus pentachloride is used as the reagent?

(a) H₂C = CH₂ → CH₃CH₂Cl

(b) CH₃CH₂OH → CH₃CH₂Cl

(c) H₃C-O - CH₃ → CH₃Cl

(d) CH - CH → CH₂ = CHCl

Answer : B

Question : The best method for the conversion of an alcohol into an alkyl chloride is by treating the alcohol with

(a) PCl₅

(b) dry HCl in the presence of anhydrous ZnCl₂

(c) SOCl₂ in presence of pyridine

(d) None of these

Answer : C

Question : Which of the following is liquid at room temperature (b.p. is shown against it) ?

(a) CH₃I 42ºC

(b) CH₃Br 3ºC

(c) C₂H₅ C l 12ºC

(d) CH₃F –78ºC

Answer : A

Question : The catalyst used in the preparation of an alkyl chloride by the action of dry HCl on an alcohol is

(a) anhydrous AlCl₃

(b) FeCl₃

(c) anhydrous ZnCl₂

(d) Cu

Answer : C

Question : Chlorobenzene is prepared commercially by

(a) Raschig process

(b) Wurtz Fittig reaction

(c) Friedel-Craft’s reaction

(d) Grignard reaction

Answer : A

Question : In the preparation of chlorobenzene from aniline, the most suitable reagent is

(a) Chlorine in the presence of ultraviolet light

(b) Chlorine in the presence of AlCl₃

(c) Nitrous acid followed by heating with Cu₂Cl₂

(d) HCl and Cu₂Cl₂

Answer : C

Question : Which of the following possesses highest melting point?

(a) Chlorobenzene

(b) m-dichlorobenzene

(c) o-dichlorobenzene

(d) p-dichlorobenzene

Answer : D

Question : Conant Finkelstein reaction for the preparation of alkyl iodide is based upon the fact that

(a) Sodium iodide is soluble in methanol, while sodium chloride is insoluble in methanol

(b) Sodium iodide is soluble in methanol, while NaCl and NaBr are insoluble in methanol

(c) Sodium iodide is insoluble in methanol, while NaCl and NaBr are soluble

(d) The three halogens differ considerably in their electronegativity

Answer : B

Question : Which of the following reactions is an example of nucleophilic substitution reaction?

(a) 2 RX + 2 Na → R – R + 2 NaX

(b) RX + H2 → RH + HX

(c) RX + Mg → RMgX

(d) RX + KOH → ROH + KX

Answer : D

Question : Which one is most reactive towards SN1 reaction ?

(a) C₆H₅CH(C₆H₅ )Br

(b) C₆H₅CH(CH₃ )Br

(c) C₆H₅C(CH₃)(C₆H₅ )Br

(d) C₆H₅CH₂Br

Answer : C

Question : A Grignard reagent may be made by reacting magnesium with

(a) Methyl amine

(b) Diethyl ether

(c) Ethyl iodide

(d) Ethyl alcohol

Answer : C

Question : Which one of the following halogen compounds is difficult to be hydrolysed by SN1 mechanism?

(a) Tertiary butyl chloride

(b) Isopropyl chloride

(c) Benzyl chloride

(d) Chlorobenzene

Answer : D

Question : The order of reactivity of the given haloalkanes towards nucleophile is :

(a) RI > RBr > KCl

(b) RCl > RBr > RI

(c) RBr > RCl > RI

(d) RBr > RI > RCl

Answer : A

Question : Most reactive halide towards SN1 reaction is

(a) n-Butyl chloride

(b) sec-Butyl chloride

(c) tert-Butyl chloride

(d) Allyl chloride

Answer : C

Question : In S_N1 reaction, the recemization takes place. It is due to

(a) inversion of configuration

(b) retention of configuration

(c) conversion of configuration

(d) Both (a) and (b)

Question : The order of reactivities of the following alkyl halides for a S_N2 reaction is

(a) RF > RCl > RBr > RI

(b) RF > RBr > RCl > RI

(c) RCl > RBr > RF > RI

(d) RI > RBr > RCl > RF

Question :  Optically active isomers but not mirror images are called

(a) enantiomers

(b) mesomers

(c) tautomers

(d) diastereomers

Question : SN₂ mechanism proceeds through intervention of

(a) carbonium ion

(b) transition state

(c) free radical

(d) carbanion

Answer : B

Question : Which among MeX, RCH₂X, R₂CHX and R₃CX is most reactive towards SN₂ reaction?

(a) MeX

(b) RCH₂X

(c) R₂ C HX

(d) R₃CX

Answer : A

Question : Isopropyl chloride undergoes hydrolysis by

(a) S_N1 mechanism

(b) S_N2 mechanism

(c) S_N1 and S_N2 mechanisms

(d) Neither S_N1 nor S_N2 mechanism

Answer : C

Question : Tertiary alkyl halides are practically inert to substitution by SN2 mechanism because of

(a) steric hindrance

(b) inductive effect

(c) instability

(d) insolubility

Answer : B

Question : Which of the following is the correct order of decreasing SN2 reactivity?

(a) R₂ C HX > R₃CX > RCH₂X

(b) RCHX > R₃CX > R₂CHX

(c) RCH₂X > R₂CHX > R₃CX

(d) R₃CX > R₂CHX > RCH₂X.

(X is a halogen)

Answer : C

Question :  Which of the following alkyl halides is used as a methylating agent?

(a) C₂H₅Br

(b) C₆H₅Cl

(c) CH₃I

(d) C₂H₅Cl

Answer : C

Question : Which of the following is an optically active compound ?

(a) 1-Butanol

(b) 1-Propanol

(c) 2-Chlorobutane

(d) 4-Hydroxyheptane

Answer : C

Question : An important chemical method to resolve a racemic mixture makes use of the formation of

(a) a meso compound

(b) enantiomers

(c) diasteromers

(d) racemates

Answer : C

Question : The process of separation of a racemic modification into d and l -enantiomers is called

(a) Resolution

(b) Dehydration

(c) Revolution

(d) Dehydrohalogenation

Answer : A

Question :  Mg reacts with RBr best in

(a) C₂H₅OC₂H₅

(b) C₆H₅OCH₃

(c) C₆H₅N(CH₃)₂ 

(d) Equally in all the three

Answer : A

Question : Which of the following will have a mesoisomer also?

(a) 2, 3- Dichloropentane

(b) 2, 3-Dichlorobutane

(c) 2-Chlorobutane

(d) 2-Hydroxypropanoic acid

Answer : B

Question : Which of the following compounds is optically active ?

(a) CH₃CHClCOOH

(b) CH₃CH₂CH₂CH₃

(c) (CH₃)₂CHOH

(d) (CH₃)₃CCl

Answer : B

Question : Racemic compound has

(a) equimolar mixture of enantiomers

(b) 1 : 1 mixture of enantiomer and diastereomer

(c) 1 : 1 mixture of diastereomers

(d) 1 : 2 mixture of enantiomers

Answer : A

Question :  2-Bromopentane is heated with potassium ethoxide in ethanol. The major product obtained is

(a) 2-ethoxypentane

(b) pentene-1

(c) trans-2-pentene

(d) cis-pentene-2

Answer : C

Question : An organic molecule necessarily shows optical activity if it

(a) contains asymmetric carbon atoms

(b) is non-polar

(c) is non-superimposable on its mirror image

(d) is superimposable on its mirror image

Answer : C

Question :   Chloroform and conc. HNO₃ react to produce

(a) CHCl₂NO₂ 

(b) CHCl₂HNO₃

(c) CCl₃NO₂   

(d) CCl₃NO₃

Answer : C

Question : Benzene diazonium chloride reacts with hypophosphorous acid to produce:

(a) phenol
(b) benzene
(c) p-hydroxyazobenzene
(d) benzonitrile

Answer : B

Question : B.H.C. is used as an

(a) Insecticide              

(b) Disinfectant

(c) Mosquito repellent  

(d) Antiseptic

Answer : A 

Question : Which one of the following produces acyl halide by treatment with PCl₅?

(a) Alcohols
(b) Esters
(c) Acids
(d) Carbonyl compounds

Answer : C

Question : 5 Gammexane is

(a) Chloral

(b) BHC

(c) DDT     

(d) HCB

Answer : B 

Question : Among the following, insecticide is

(a) BHC     

(b) Phosphene

(c) Chloral 

(d) Aspirin

Answer : A 

Question : Which of the following is a chiral compound?

(a) hexane
(b) n-butane
(c) methane
(d) 2,3,4-trimethylhexane

Answer : D 

Question : Which of the following is most stable?

(a) 1-butene

(b) 1-pentene

(c) 2-butene

(d) 2-pentene

Answer : C 

Question : Among the following, the most reactive towards alcoholic KOH is :

(a) CH₂=CHBr

(b) CH₃COCH₂CH₂Br

(c) CH₃CH₂Br

(d) CH₃CH₂CH₂Br

Answer : B

Question : Among the following, the dissociation constant is highest for 

Answer : D