CBSE Class 12 Chemistry Haloalkanes and Haloarenes MCQs Set D

Question: The order ofreactivities of methyl halides in the formation of Grignard reagent is 
(a) CH₃l > CH₃Br > CH₃CI
(b) CH₃Cl > CH₃Br > CH₃I
(c) CH₃Br > CH₃CI > CH₃I
(d) CH₃Br > CH₃l > CH₃Cl
Answer: a

Question: Number of monochloro derivatives obtained when neo-pentane is chlorinated, is
(a) one
(b) two
(c) three
(d) four
Answer: a

Question: Which of the following is not true for the hydrolysis of t-butyl bromide with aqueous NaOH? 
(a) Reaction occurs through the S_N1 mechanism
(b) The intermediate formed is a carbocation
(c) Rate of the reaction doubles when the concentration of alkali is doubled
(d) Rate of the reaction doubles when the concentration of t-butyl bromide is doubled
Answer: c

Question: Grignard reagent is not prepared in aqueous medium but prepared in either medium, because 
(a) the reagent is highly reactive in ether
(b) the reagent does not react with water
(c) the reagent becomes inactive in water
(d) the reagent reacts with water
Answer: d

Question: Ethyl iodide when heated with sodium in dry ether gives pure 
(a) C₄H₁₀
(b) C₂H₆
(c) C₃H₈
(d) C₂H₅OH
Answer: a

Question: Which of the following alkyl halides is used as a methylating agent?
(a) C₂H₅Br
(b) C₆H₅Cl
(c) CH₃CI
(d) C₂H₅Cl
Answer: a

Question: CH₃Br + KCN (ale. ) → X Reduction→_{Na +C2H5 OH} Y. What is Y in the series ? 
(a) CH₃CN
(b) C₂H₅CN
(c) C₂H₅NH₂
(d) CH₃NH₂
Answer: c

Question: In a group of isomeric alkyl halides, the order of boiling points is 
(a) primary < secondary < tertiary
(b) primary > secondary < tertiary
(c) primary < secondary > tertiary
(d) primary > secondary > tertiary
Answer: d

Question: Alkyl halide is converted into alcohol. This is an example of ...... reaction. 
(a) addition
(b) displacement
(c) substitution
(d) complex
Answer: c

Question: Maximum number of molecules of CH₃l that can react with a molecule of CH₃NH₂ are 
(a) 3
(b) 4
(c) 2
(d) 1
Answer: a 

Question: The conversion of ethyl chloride into diethyl ether takes place by 
(a) Williamson's synthesis
(b) Perkin's reaction
(c) Wurtz reaction
(d) Grignard reaction
Answer: a

Question: Elimination of bromine from 2-bromobutane results in the formation of
(a) predominantly 2-butyne
(b) predominantly 1-butene
(c) predominantly 2-butene
(d) equimolar mixture of 1 and 2-butene
Answer: c

Question: In the reaction, 2A + dry silver oxide →^Δ ether+ 2Ag X A is a /an 
(a) primary alcohol
(b) acid
(c) alkyl halide
(d) alcohol
Answer: c

 Question: An alkyl halide reacts with alcoholic ammonia in a sealed tube, the product formed will be
(a) a primary amine
(b) a secondary amine
(c) a tertiary amine
(d) All of the above
Answer: d

 Question: The organic chloro compound, which shows complete stereochemical inversion during an S_N2 reaction is
(a) (C₂H₅)₂CHCl
(b) (CH₃)₃CCl
(c) (CH₃)₂CHCl
(d) CH₃Cl
Answer: d 

Question: 9.65 C of electric current is passed through fused anhydrous magnesium chloride. The magnesium metal thus, obtained is completely converted into a Grignard reagent. The number of moles of the Grignard reagent obtained is 
(a) 5 x 10^-4
(b) 1 x 10^-4
(c) 5 x 10^-5
(d) 1 x 10^-5
Answer: c

Question: Which one of the following forms propane nitrile as the major product? 
(a) Ethyl bromide + alcoholic KCN
(b) Propyl bromide + alcoholic KCN
(c) Propyl bromide + alcoholic AgCN
(d) Ethyl bromide + alcoholic AgCN
Answer: a

Question: Tertiary butyl alcohol gives tertiary butyl chloride on treatment with 
(a) cone. HCl/anhy. ZnCl₂
(b) KCN
(c) NaOCI
(d) Cl₂
Answer: a

Question: The product of reaction between alcoholic silver nitrite with ethyl bromide is 
(a) ethene
(b) ethane
(c) ethyl nitrile
(d) nitro ethane
Answer: d

Question: 2-bromopentane with ale. KOH yields a mixture of three alkenes. Which of the following alkene is predominant?
(a) 1-pentene
(b) Cis-2-pentene 
(c) Trans-2-pentene
(d) Cis-1-pentene
Answer: c

Question: Reaction of trans-2-phenyl-l-bromo reaction with alcoholic KOH produces cyclopentane on
(a) 4-phenyl cyclopentene
(b) 2-phenyl cyclopentene
(c) 1-phenyl cyclopentene
(d) 3-phenyl cyclopentene
Answer: d

Question: The catalyst used in the preparation of an alkyl chloride by the action of dry HCI on an alcohol is
(a) anhy. AlCl₃ 
(b) FeCl₃
(c) anhy. ZnCl₂
(d) Cu
Answer: c

Question: Alkyl halides are less soluble in water because
(a) they ionise in water
(b) they do not form H-bonds with water
(c) they are highly viscous
(d) they have very strong C—X bond
Answer: b

Question: 1-chlorobutane on reaction with alcoholic potash gives
(a) 1-butene
(b) 1-butanol 
(c) 2-butene
(d) 2-butanol
Answer: a

Question: In S_N 2 reactions, the correct order of reactivity for the following compounds CH₃ Cl, CH₃CH₂ Cl, (CH₃)₂ CHCI and (CH₃)₃ CCI is
(a) CH₃CI > (CHH₃)₂ CHCI > CH₂CH₂CI > (CH₃)₃ CCI
(b) CH₃Cl > CH₃CH₂Cl > (CH₃)₃ CHCI > (CH₃)₃CCI
(c) CH₃CH₂Cl > CH₃Cl > (CH₃ )₂ CHCI >(CH₃)₃ CCI
(d) (CH₃)₂ CHCI > CH₃CH₂Cl > CH₃Cl > (CH₃)₃ CCI
Answer: b

Question: CH₃Br + OH → CH₃OH + Br^- reaction proceeds by S_N2 mechanism. Its rate is dependent on the concentration of 
(a) CH₃Br, OH
(b) Only CH₃Br
(c) Only OH
(d) CH₃Br, CH₃OH
Answer: a

Question: 1 , 2-dibromoethane reacts with alcoholic KOH to yield a productX. The hybridisation state of the carbons present in X respectively, are 

(a) sp ,sp
(b) sp³ , sp³
(c) sp³ , sp²
(d) sp³ , sp²
Answer: a

Question: Which of the following statements regarding the S_N1 reaction shown by alkyl halide is not correct?
(a) The added nucleophile plays no kinetic role in S_N1 reaction
(b) The S_N1 reaction involves the inversion of configuration of the optically active substrate
(c) The S_N1 reaction on the chiral starting material ends up with racemisation of the product
(d) The more stable the carbocation intermediate the faster the S_N1 reaction
(e) Polar pro tic solvent increases the rate of S_N1 reaction.
Answer: b

Question: The best method for the conversion of an alcohol into an alkyl chloride is by treating the alcohol with
(a) PCl₃
(b) PCl₅
(c) SOCl₂ in the presence of pyridine
(d) dry HCl in the presence of anhydrous ZnCI₂
Answer: c

Question: Compound 'A' reacts with alcoholic KOH to yield compound 'B ', which on ozonolysis followed by reaction with Zn /H₂O gives methanal and propanal. Compound 'A' is 
(a) 1-propanol
(b) 1-butanol
(c) 1-chlorobutane
(d) 1-chloropentane
Answer: c

Question: Identify A and B in the following reactions
A →^{Aq. NaOH} C₂H₅ OH ^AgOH_← B
(a) A = C₂H₂, B = C₂H₆
(b) A = C₂H₅ Cl,B = C₂H₄
(c) A = C₂H₄ , B = C₂H₅ Cl
(d) A = C₂H₅ Cl,B = C₂H₅ Cl
Answer: d

Question: The order of reactivities of methyl halides in the formation of Grignard reagent is 
(a) CH₃I > CH₃Br > CH₃CI
(b) CH₃CI > CH₃Br > CH₃I
(c) CH₃Br > CH₃CI > CH₃I
(d) CH₃Br > CH₃I > CH₃CI
Answer: a

Question: Tertiary alkyl halides are practically inert to substitution by S_N2 mechanism because of
(a) steric hindrance
(b) inductive effect
(c) instability
(d) insolubility
Answer: a

Question: Identify X and Y in the following sequence :
C₂H₅ Br → product → C₃H₇NH₂
(a) X = KCN,Y = LiAIH₄
(b) X = KCN,Y = H₃O₊
(c) X = CH₃Cl,Y = AlCl₃ / HCI
(d) X = CH₃NH₂ ,Y = HNO₂
Answer: a

Question: Which halide does not get hydrolysed by sodium hydroxide? 
(a) Vinyl chloride
(b) Methyl chloride
(c) Ethyl chloride
(d) Iso-propyl chloride
Answer: a

Question: An alkyl halide (RX) reacts with Na to form 4, 5-diethyloctane. Compound RX is
(a) CH₃ (CH₂)₃ Br
(b) CH₃ (CH₂)₂CH(Br)CH₂CH₃
(c) CH₃ (CH₂)₃CH(Br)CH₃
(d) CH₃ (CH₂)₅ Br
(e) CH₃Br
Answer: b

Question: Which one of the following is more readily hydrolysed by S_N1 mechanism? 
(a) (C₆H₅)₂ C(CH₃)₂
(b) C₆H₅CH₂Br
(c) C₆H₅CH(CH₃) Br
(d) (C₆H₅)₂ CHBr
Answer: b

Question: Alkyl iodide reacts with NaCN to give alkyl cyanide and small amount of alkyl isocyanide. Fom1ation of these two products is due to the 
(a) ionic character of NaCN
(b) nucleophilic character of CN^-
(c) ambidentate character of CN^-
(d) electrophilic character of CN^-
Answer: c

Question: Of the isomeric hexanes, the isomers that give the minimum and maximun number of monochloro derivatives are respectively 
(a) 3-methyl pentane and 2, 3-dimethyl butane
(b) 2, 3-dimethy 1 butane and n-hexane
(c) 2, 2-dimethye 1 butane and 2-methy 1 pentane
(d) 2, 3-dimethy 1 butane and 2-methy 1 pentane
(e) 2-methyl pentane and 2, 2-dimethylbutane 
Answer: d

Question: 1-chlorobutane on reaction with alcoholic potash gives
(a) but-1-ene
(b) butane-1-ol 
(c) but-2-ene
(d) butane-2-ol
Answer: a

Question: When 32.25 g of ethyl chloride is subjected to dehydrohalogenation reaction the yield of the alkene formed is 50%. The mass of the product formed is (atomic mass of chlorine is 35.5)
(a) 14 g
(b) 28 g
(c) 64.5 g
(d) 56 g
(e) 7 g
Answer: e

Question: Anti-Markownikoff's addition of HBr is observed in
(a) propane
(b) but-2-ene
(c) pent-2-ene
(d) All of the above
Answer: a

Question: An incorrect statement with respect to S_N1 and S_N2 mechanisms of alkyl halide is 
(a) a strong nucleophile in an aprotic solvent increases the rate or favours S_N2 reaction
(b) competing reaction for a S_N2 reaction is rearrangement
(c) S_N1 reactions can be catalysed by some Lewis acids
(d) a weak nucleophile and aprotic solvent increases the rate or favours S_N1 reaction
Answer: b

Question: Which reagents would you use to carry out the reaction Ethyl benzene → 2 and 4-chloro- 1 -ethyl benzene?
(a) Cl₂, light and heat 
(b) Cl₂, FeCl₃
(c) SOCl₂
(d) C₂H₅CI, AICl₃
Answer: b

Question: Which of the following haloalkanes is most reactive?
(a) 1-chloropropane
(b) 1-bromopropane 
(c) 2-chloropropane
(d) 2-bromopropane
Answer: d 

Question: On treating a mixture of two alkyl halides with sodium metal in dry ether, 2-methyl propane was obtained. The alkyl halides are 
(a) 2-chloropropane and chloromethane
(b) 2-chloropropane and chloroethane
(c) chloromethane and chloroethane
(d) chloromethane and 1-chloropropane
Answer: a 

Question: Which one of the following is not fom1ed when a mixture of methyl bromide and bromobenzene is heated with sodium metal in the presence of dry ether? 
(a) Diphenyl
(b) Propane
(c) Toluene
(d) Ethane
Answer: b

Question: RX+ A → RNC,A is
(a) AgCN
(b) KCN
(c) NaCN
(d) HCN
Answer: a 

Question: Ethyl chloride on heating with AgCN forms a compound X. The functional isomer of X is 
(a) C₂H₅NC
(b) C₂H₅NH₂
(c) C₂H₅CN
(d) None of these
Answer: c 

Question: CH₃Br + Nu^- → CH₃ —Nu + Br^- . The decreasing order of the rate of the above reaction with nucleophiles (Nu^-) A to D is
 [Nu^- = (A) PhO^-, (B) AcO^- , ( C) HO^- ],(D) CH₃O^- )
(a) D > C > A > B
(b) D > C > B > A 
(c) A > B > C > D
(d) B > D > C > A
Answer: a

Question: X + KCN → CH₃CN →^2H₂/Ni CH₃CH₂NH₂ What is X ? 
(a) CH₃CH₂Cl
(b) CH₃CI
(c) CH₃CH₂CH₂Cl
(d) (CH₃)₂CHCl
Answer: b 

Question: Of the five isomeric hexanes, the isomer which can give two monochlorinated compounds is 
(a) 2-methy 1 pentane
(b) 2, 2-dimethy 1 butane
(c) 2, 3-dimethyl butane
(d) n-hexane
Answer: c

Question: Which of the following compounds has the highest boiling point? 
(a) CH₃CH₂CH₂Cl
(b) CH₃CH₂CH2CH₂Cl
(c) CH₃CH(CH₃)CH₂Cl
(d) (CH₃)₃ CCI 
Answer: b

Question: t-butyl chloride preferably undergo hydrolysis by 
(a) S_N1 mechanism
(b) S_N2 mechanism
(c) Any of (a) and (b)
(d) None of the above
Answer: a

Question: In the following sequence of reactions, 
C₂H₅Br →^AgCN X →^Reduction Y , Y IS
(a) n-propylamine
(b) iso-propylamine
(c) ethylamine Reduction 
(d) ethyl methyl amine
Answer: d

Question: Which of the following applies in the reaction,
CH₃CHBrCH₂CH₃ →^{Ale. KOH}
I. CH₃CH = CHCH₃ (major product)
II. CH₂ = CHCH₂CH₃ (minor product)
(a) Markownikoff's rule
(b) Saytzeff's rule
(c) Kharasch effect
(d) Hofrnann's rule
Answer: b

Question: Following is the substitution reaction in which —CN replaces —CL
R—Cl + KCN_Alcoholic →^Δ R—CN + KCl
To obtain propane nitrile, R—Cl should be 
(a) chloroethane
(b) 1-chloropropane
(c) chloromethane
(d) 2-chloropropane 
Answer: a