CBSE Questions for Class 12 Engineering Chemistry Haloalkanes And Haloarenes Quiz 1 - MCQExams.com

An unknown alkyl halide $$[$$X$$]$$ reacts with alcoholic KOH and produces a hydrocarbon $$(C_4H_8)$$ as the major product. Ozonolysis of this hydrocarbon affords one mole of propanaldehyde and one mole of formaldehyde. Suggest which organic compound among the following has the correct structure of the above alkyl halide $$[$$X$$]$$?
  • $$CH_3CH_2CH_2CH_2Br$$
  • $$CH_3CH(Br)CH_2CH_3$$
  • $$CH_3CH(Br)CH(Br)CH_3$$
  • $$Br(CH_2)_4Br$$
In alkaline hydrolysis of tertiary halide by aqueous alkali if concentration of alkali doubled, then the reaction:
  • will be doubled
  • will be halved
  • will remain constant
  • None of the above
An alkane $$C_6H_{14}$$ gives only two monochloro derivatives on chlorination. Its possible structure is:
  • $$CH_3CH_2CH_2CH_2CH_2CH_3$$
  • $$CH_3-{\underset{\displaystyle CH_3}{\underset{|}CH}}-CH_2CH_2CH_3$$
  • $$CH_3CH_2-{\underset{\displaystyle CH_3}{\underset{|}CH}}

    -CH_2CH_3$$
  • $$CH_3-{\overset{\displaystyle CH_3}{\overset{|}CH}}-{\overset{\displaystyle CH_3}{\overset{|}CH}}-CH_3$$
Identify $$X$$ and $$Y$$ in the following reaction.
$$H_ 2\underset { \underset {\displaystyle Br }{ | }  }{ C } -\underset { \underset { \displaystyle Br }{ | }  }{ CH_2}+KOH\xrightarrow [  ]{ alcohol } X\xrightarrow [  ]{ NaNH_ 2 } Y$$
  • $$X: CH_3CHBr,  \,\,Y: CH_2=CH_2$$
  • $$X: CH_2OH-CH_2OH, \,\, Y: CH_2=CH_2$$
  • $$X: CH_2=CHBr, \,\, Y: CH\equiv CH$$
  • $$X: CH\equiv CBr, \,\, Y: CH\equiv CH$$
$$2-$$$ Bromopentane is treated with alcoholic $$KOH$$ solution. What will be the major product formed in this reaction and what is this type of elimination called?
  • Pent $$-1-$$ ene, $$\beta$$- Elimination
  • Pent $$-2-$$ ene, $$\beta$$- Elimination
  • Pent $$-1-$$ ene, Nucleophilic substitution
  • Pent $$-2-$$ ene, Nucleophilic substitution
In halogenation of aromatic hydrocarbon, a halogen carrier is used which is generally a Lewis acid. The main function of this reagent is to generate the species :
  • $$ X $$
  • $$ X^- $$
  • $$ X^+ $$
  • $$ X^{\bullet}$$
The correct decreasing order of following alkyl halides according to the rate of $$\beta$$ - elimination reaction with alcoholic KOH will be:
(i)$${ CH }_{ 3 }-\overset { \underset { | }{ H }  }{ \underset { \underset { { CH }_{ 3 } }{ | }  }{ C }  } -{ CH }_{ 2 }Br$$
(ii) $$ CH_3-CH_2-Br$$
(iii) $$CH_3-CH_2-CH_2-Br$$
  • (i) > (ii) > (iii)
  • (iii) > (ii) > (i)
  • (ii) > (iii) > (i)
  • (i) > (iii) > (ii)
Which of the following compounds will react with Na to form 4,5- diethyloctane?
  • $$CH_3CH_2CH_2CH_2Br$$
  • $$CH_3CH_2CH_2-{\underset{CH_3}{\underset{|}C}H}-CH_2CH_2Br$$
  • $$CH_3CH_2CH_2CH_2-{\underset{Br}{\underset{|}C}H}-CH_3$$
  • $$ CH_3CH_2CH_2-{\underset{Br}{\underset{|}C}H}-CH_2CH_3$$
Which of the following is a primary halide?
  • iso-propyl iodide
  • sec-butyl iodide
  • tert-butyl bromide
  • neo-hexyl chloride
$$S_N1$$ reaction is fastest in?
  • $$CH_3CH_2Br$$
  • $$CH_3-{\underset{CH}{\underset{|}{CH}}}-Cl$$
  • $$CH_3-{\underset{Ch_3}{\underset{|}{\underset{CH_2}{\underset{|}{CH}}}}}-Cl$$
Which of the following compounds can yield only one monochlorinated product upon free radical chlorination?
  • 2, 2-Dimethyipropane
  • 2-Methylpropane
  • 2-Methylbutane
  • n-Butane
Which of the following statement regarding the $$S_N1$$ reaction shown by alkyl halide is correct?
  • The added nucleophile plays no kinetic role in $$S_N1$$ reaction.
  • The $$S_N1$$ reaction involves the inversion of the configuration of the optically active substrate
  • The $$S_N1$$ reaction on the chiral starting material ends up with racemisation o f the product.
  • The more stable the carbocation intermediate the faster the $$S_N1$$ reaction.
Which of the following alkyl halides is hydrolysed by $$S_N1$$ mechanism?
  • $$CH_3Cl$$
  • $$CH_3CH_2Cl$$
  • $$CH_3CH_2CH_2Cl$$
  • $$(CH)_3CCl$$
2,4-hexadiyne $$(C_6 H_6)$$ is allowed to react with $$Li$$ in $$NH_3$$(liq). The product obtained is treated with 1 equivalent of $$Cl_2$$ $$CCl_4$$. Which of the following constitutional isomers are possible products ?
989456_310da20d56ed49ff82bb122580792def.png
  • I and II
  • II and III
  • I and IV
  • I and III
Major product is:
1154044_c26557faac4d4c419f3e1eb3ae184a1b.png
Which of the following isomer of C$$_{5}$$H$$_{11}$$Cl exhibits optical isomerism?
  • 1-chloropentane
  • 2-chloro-2-methylpentane
  • 2-chloro-3-methylbutane
  • 1-chloro-2,2-dimethylpropane
$${CH}_{3}-I+2Na+I-{CH}_{3}\xrightarrow [  ]{dry \; ether } $$ _______
  • $${C}_{2}{H}_{5}-{C}_{2}{H}_{5}$$
  • $${CH}_{4}$$
  • $${C}_{3}{H}_{8}$$
  • $${CH}_{3}-{CH}_{3}$$
Which of the following alkyl bromides undergoes most rapid solvolysis in methanol solution to give corresponding methyl ether ?
What is the minimum quantity (in grams) of methyl bromide required for preparing one mole of ethane by wurtz reaction?
  • 188
  • 109
  • 326
  • 284
Pure methane can be produced by:
  • Wurtz reaction
  • Kolbe's electrolytic
  • soda lime decarboxylation
  • reduction with $$H_2$$
Which type of isomerism can not be shown by benzaldoxime ?
  • Optical isomerism
  • Functional group isomerism
  • Geometrical isomerism
  • Configuration isomerism
Given Reaction.
Y in reaction is:
1189053_2c8eac8ff1bc40c9b459e7069674e8c1.png
  • Hexane
  • Cyclohexane
  • Cyclohexylcyclohexane
  • Cyclohexylether
What is the CORRECT order of reactivity of the following compounds in atomic nucleophilic substitution reaction when treated with aq. NaOH?
1262498_0fe623a0887a4c7dba9b4dca3363d9e1.png
  • I > II > II IV
  • IV > III > II > I
  • II > III > I > IV
  • IV > II > I > III
Consider the reaction -The major product $$A$$ is?

1289412_54011985b68d4748a5980ad902718e6e.png
The following stability of the following carbon cations:
1279988_1c518e9b99d34c27a66a43a606299ca8.png
  • III > II >I
  • II > III > I
  • I > II > III
  • III > I > II
Which of the following is a correct order of reactivity of chlorides for given compounds ?
1268243_6df5d3921cff43d7b0a19e79c49555db.png
  • $$I > II > III > IV > V $$
  • $$ I > III > II > IV > V $$
  • $$ III > I > IV > V > II $$
  • $$ I > III > IV > V > II $$
Chlorobenzene is prepared commercially by 
  • Raschig process
  • Wurtz Fitting reaction
  • Friedel-Craft's reaction
  • Grignard reaction
To prepare a pure sample of normal hexane using sodium metal as one reactant, the other reactant or reactants will be:
  • Ethyl chloride and n-butyl chloride
  • Methyl bromide and n-pentyl bromide
  • n-propyl bromide
  • ehtyl bromide and n-butyl bromide
Which is intermediate of above reaction : 
1348274_e46cebebaaf54a4baf61c8fa2d3162db.png
When octa-O-methyl d-cellobiose is hydrolysed by aqueous acid, two O-methylated glucose derivatives are formed:  One is tetramethyl derivative and the other is trimethyl derivative. Why is a single methyl substituent lost in this process ? 
  • One methoxy group is lost by  $$ \beta $$ -elimination
  • One methoxy group is an ester and the others are all ethers
  • One methoxy group is a part of an acetal,the others are all ethers
  • One glucose is an $$\alpha$$-methyl glycoside, the other is a $$\beta$$-methyl glycoside
The major product of the following reaction is :
1316865_0edd289c5f004bd29d61ee3d9c735b30.png
2-choloro-2-methylpentane on reaction with sodium methoxide in methanol yields
  • None of these
$$wC_{2}H_{6}+xI_{2}+HIO_{3}\rightarrow y C_{2}H_{5}I+z H_{2}O$$ the value of $$w,x,y,z$$ are:
  • $$5,2,5,3$$
  • $$5,5,2,3$$
  • $$5,3,5,2$$
  • $$2,2,2,1$$
Preparation of alkyl halides in laboratory is least preferred by :
  • Halide exchange
  • Direct halogenation of alkanes
  • Treatment of alcohols
  • Addition of hydrogen halides to alkenes
In the question arrange the compounds in increasing order of rate of reaction towards nucleophilic substitution.
1847652_44acb10853564f0c96e27cc00344ce43.png
  • (I) < (II) < (III)
  • (III) < (II) < (II)
  • (I) < (III) < (II)
  • (III) < (I) < (II)
Reaction of trans-2-phenyl-1-bromocyclopentane on reaction with alcoholic KOH produces
  • 4-phenylcyclopentene
  • 2-phenylcyclopentene
  • 1-phenylcyclopentene
  • 3-phenylcyclopentene
State whether the statement is true or false. Rewrite the false statement correctly.
Wurtz reaction can be used to prepare alkanes with odd number of carbon atoms.
  • True
  • False
The product of the reaction is :

14605_893342803df34b34a9f55f4bc81f8e51.png
An alkyl halide on reaction with sodium in the presence of ether gives 2,2,5,5-tetramethylhexane. The alkyl halide is:
  • 1-chloro pentane
  • 1-chloro-2,2-dimethyl propane
  • 3-chloro-2,2-dimethyl butane
  • 2-chloro-2-methyl-butane
Addition of ethanol aqueous, to the benzyl chloride does not increase the rate of the
hydrolysis but changes only the composition of the final products. This indicates that the reaction is proceeding through:
  • $$S_{N}1$$ mechanism
  • $$S_{N}2$$ mechanism
  • $$S_{E}1$$ mechanism
  • $$S_{E}2$$ mechanism
Statement 1: $$S_{N}2$$ reaction is carried out in the presence of polar aprotic solvents. 
Statement 2: Polar aprotic solvents does not contain acidic hydrogen.
  • Statement 1 and Statement 2 are correct and Statement 2 is the correct explanation for Statement 1.
  • Statement 1 and Statement 2 are correct and Statement 2 is not the correct explanation for Statement 1.
  • Statement 1 is correct and statement 2 is wrong.
  • Statement 1 is wrong and statement 2 is correct.
The major product obtained in the photo catalysed bromination of $$2$$-methylbutane is:
  • $$1$$-bromo-$$2$$-methylbutane
  • $$1$$-bromo-$$3$$-methylbutane
  • $$2$$-bromo-$$3$$-methylbutane
  • $$2$$-bromo-$$2$$-methylbutane
Which one of the following occurs by an addition elimination mechanism?
  • Toluene, Br$$_2$$, FeBr$$_3 \rightarrow$$ $$\rho$$-bromotoluene
  • Benzene, HNO$$_3$$, H$$_2$$SO$$_4 \rightarrow$$ nitrobenzene
  • Benzene, CO, HCl, AlCl$$_3$$, CuCl $$\rightarrow$$ benzaldehyde
  • 2, 4-dinitrochlorobenzene, NaOH, heat, then H$$^+ \rightarrow$$ 2, 4-dinitrophenol
The following synthesis can not be carried out by:
117515_68a9cba6577b48b695033678b0431bd5.png
  • $$\xrightarrow [(1)]{Cl_2}$$ $$\xrightarrow [(2)]{ICl/ CH_3COOH}$$ $$\xrightarrow [(3)]{ICl/CH_3COOH}$$ $$\xrightarrow [(4)]{Zn dust}$$
  • $$\xrightarrow [(1)]{HOBr/H^+}$$ $$\xrightarrow [(2)]{Cl_2/Fe}$$ $$\xrightarrow [(3)]{ICl/ZnCl_2(excess)}$$ $$\xrightarrow [(4)]{NaOH, \Delta}$$
  • $$\xrightarrow [(1)]{HOBr/H^+}$$ $$\xrightarrow [(2)]{Cl_2/Fe}$$ $$\xrightarrow [(3)]{ICl/ZnCl_2(excess)}$$ $$\xrightarrow [(4)]{Zn dust, CH_2COOH}$$
  • $$\xrightarrow [(1)]{Br_2/CH_3COOH}$$ $$\xrightarrow [(2)]{Cl_2/Fe}$$ $$\xrightarrow [(3)]{ICl/CH_3COOH (excess)}$$ $$\xrightarrow [(4)]{NaNH_2}$$
The product of the reaction $$P$$ is:

128350_bb3170749ce74a0889e3cf63a77ec2da.png
  • None of the above
In the given reaction, the products are:

128363_4c3281968a4b43f0a75a37ef128ae124.png
In the reaction $$C_{7}H_{8}\xrightarrow {3Cl_{2}/\Delta}X\xrightarrow {Br_{2}/Fe} Y \xrightarrow {Zn/HCl}Z$$.

The compound $$Z$$ is :
  • o-bromotoluene
  • m-bromotoluene
  • p-bromotoluene
  • 3-bromo-2, 2, 6-trichlorotoluene
Consider the following reaction, expected to be occuring by $$ ' E-i cb' $$ mechanism 
$$PH-CH_2 - \underset { \overset { | }{ Br }  }{ CH } -CH_2+C_2H_5OK\xrightarrow [  ]{ C_2H_2OD } $$
Which is least expected compound in the reaction mixture:
  • $$ PhCH = CHCH_3 $$
  • $$ \underset { \overset { | }{ D } }{ PhCH } -\underset { \overset { | }{ Br } }{ CH } -CH_3 $$
  • $$ Ph-CH2-\overset { \underset { | }{ Br } }{ \underset { \overset { | }{ D } }{ C } } -CH3 $$
  • $$ Ph-\underset { \overset { | }{ D } }{ C } =CH-CH_3 $$

Which of the given molecules are optically active?
760667_bd2a1b1ad7d34ba28e2dbab009788a23.png
  • (i) and (iii)
  • (ii) and (iii)
  • (i), (ii) and (iii)
  • (i) and (ii)
Deduce structure $$(A)$$.

$$(A)\ { C }_{ 8 }{ H }_{ 10 }\xrightarrow [ ]{ KMn{ O }_{ 4 } } (B)\quad { C }_{ 8 }{ H }_{ 6 }{ O }_{ 4 }\xrightarrow [ Fe ]{ { Br }_{ 2 } } (C)\quad { C }_{ 8 }{ H }_{ 5 }{ BrO }_{ 4 }$$ (one product only)
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