CBSE Questions for Class 12 Engineering Chemistry Haloalkanes And Haloarenes Quiz 6 - MCQExams.com

Ethyl chloride is converted to butane by :
  • Kolbes synthesis
  • Williamson's synthesis
  • Wurtz reaction
  • Gattermann reaction
Chloroethane is reacted with alcoholic potassium hydroxide. The product formed is:
  • $$C_{2}H_{6}O$$
  • $$C_{2}H_{6}$$
  • $$C_{2}H_{4}$$
  • $$C_{2}H_{4}O$$
Reaction of ethyl chloride with sodium leads to (in the presence of dry ether):
  • ethane
  • propane
  • n-butane
  • n-pentane
$$1$$-Chlorobutane on reaction with alcoholic potash gives:
  • $$1$$-butene
  • $$1$$-butanol
  • $$2$$-butene
  • $$2$$-butanol
Which of the following is not true for $$S_{N}1$$ reactions ?
  • These occur through a single step.
  • These are favoured by polar solvents.
  • $$3^{o}$$ alkyl halides generally react through this mechanism.
  • Concentration of nucleophile does not affect the rate of such reactions.
$$C_6H_5-\!\!\!\!\!\underset{H}{\underset{|}{\overset{\,\,\,\,\,\,CH_3}{\overset{|}{C}}}}\!\!\!\!\!-Br+H_2O \to HO -\!\!\!\!\!\underset{H}{\underset{|}{\overset{\,\,\,\,\,\,CH_3}{\overset{|}{C}}}}\!\!\!\!\! -C_6H_5+HBr$$

The above reaction result in 98% racemization, the reaction mainly follows:
  • $$S_{N}1$$ mechanism
  • $$S_{N}2$$ mechanism
  • $$E^{1}$$ mechanism
  • $$E^{2}$$ mechanism
Reaction of Chlorobenzene with $$CH_3Cl$$ in presence of $$AlCl_{3}$$ gives:
  • Toulene
  • m-chloro toulene
  • Only o-chloro toulene
  • Mixture of o- and p-chlorotoulene
The correct match is :
  List-I  List-II
 A $$C_2H_5Cl$$ 1 Williamson synthesis
 B R-X+Mg+dry ether 2 Wurtz reaction
 C $$C_2H_5Cl+C_2H_5ONa$$ 3 Anaesthetic
 D Na+dry ether  4 Antiseptic
   5 Grignard reagent
  • $$A-3, B-5, C-1, D-2$$
  • $$A-5, B-3, C-1, D-2$$
  • $$A-3, B-4, C-1, D-2$$
  • $$A-3, B-5, C-1, D-4$$
The IUPAC name is:  $$H-\underset{H}{\underset{|}{\overset{H}{\overset{|}{C}}}}-\underset{H}{\underset{|}{\overset{Cl}{\overset{|}{C}}}}-Cl$$
  • $$1,2$$ - dichoroethane
  • $$2,2$$ - dichloroethane
  • $$1,1$$ - Dichloroethane
  • dichloroethane
Which of the following statement is not correct?
  • Chlorobenzene is more reactive than benzene towards electrophilic substitution
  • $$C- Cl$$ bond in chlorobenzene is less polar than $$CH Cl_{3}$$
  • Chlorobenzene is less reactive than $$CH Cl_{3}$$
  • In chlorobenzene further substitution takes place at ortho and para positions
Which of the following molecules is expected to rotate the plane of plane-polarised light?
Which of these is o, p-directing and deactivating group?
  • $$-F$$
  • $$-Cl$$
  • $$-Br$$
  • All of these
The compound $$X$$ is:
15398.png
  • o-methylchlorobenzene
  • p-methylchlorobenzene
  • m-methylchlorobenzene
  • both $$A$$ & $$B$$
The reaction of toluene with $$Cl_{2}$$ in presence of $$Fe$$, the product(s) formed is/are:
  • o- and p-chlorotoluene
  • benzyl chloride
  • m-chlorotoluene
  • only p-chlorotoluene
If $$C_{4}H_{9}Cl$$ with $$Na/ether$$ gives $$2,5$$-dimethylhexane, then the compound, $$C_{4}H_{9}Cl$$ is:
  • n-butylchloride
  • sec-butylchloride
  • iso-butylchloride
  • tert-butylchloride
In the following pair of compounds, which compound is more nucleophilic in a polar-protic solvent? 
  
        $${ CH }_{ 3 }Cl$$ or $${ CH }_{ 3 }OH$$
  • $${ CH }_{ 3 }Cl$$
  • $${ CH }_{ 3 }OH$$
  • $${ CH }_{ 3 }Cl = { CH }_{ 3 }OH$$
  • None of these

For the given pair of $${{ S }_{ N }}1$$ reactions, the ______ reaction is faster.
141167.png
  • first
  • second
  • both progress at the same rate
  • cannot be determined
Which of the following relation is correct for recativity?

$${ CH }_{ 3 }COO^{ - }$$ or $${ CH }_{ 3 }{ CH }_{ 2 }S^{ - }$$ with $${ CH }_{ 3 }I$$ in ethanol.
  • $${ CH }_{ 3 }{ CH }_{ 2 }S^{ - } > { CH }_{ 3 }COO^{ - }$$
  • $${ CH }_{ 3 }{ CH }_{ 2 }S^{ - } < { CH }_{ 3 }COO^{ - }$$
  • $${ CH }_{ 3 }{ CH }_{ 2 }S^{ - } = { CH }_{ 3 }COO^{ - }$$
  • None of these
Which of the given pair of $${ S }_{ N }1$$ reaction would you expect to proceed faster? Explain your answer.

141353.png
  • $${3}^{o}$$-alcohol > $${2}^{o}$$-alcohol
  • $${3}^{o}$$-alcohol < $${2}^{o}$$-alcohol
  • $${3}^{o}$$-alcohol = $${2}^{o}$$-alcohol
  • None of these
Which of the following chlorides is highly reactive in $${{ S }_{ N }}1$$ reaction, even solvolysed in cold water?
  • None of the above

Statement: In the above reaction,  first compound in the product side is the major product.

State whether the given statement is true or false

141360_68482d53f4b249fe815fef48ff8e200f.png
  • True
  • False
Which of the following statements/reactions are correct?
  • $$S_N2/E2$$ ratio is higher with $$RS^{\circleddash}$$ than for those with $$RO^{\circleddash}$$
  • $$S_N2/E2$$ ratio is higher for $$1^o RX$$ and least for $$3^oRX$$
  • $$Me_3C-Br+KCN\longrightarrow Me_3C-CN$$
  • None of the above
The alkyl halides required to prepare $$(CH_3)_2CH-CH_2-CH_2-CH_3$$ by Wurtz reaction are:
$$\underset { Specific\quad rotaion=+{ 50 }^{ o } }{ Ph-CH(OH){ CH }_{ 3 } } \xrightarrow [  ]{ SO{ Cl }_{ 2 } } \quad \underset { |\\ Cl }{ PhCl } -{ CH }_{ 3 }$$
Which of the following mechanisms does the reaction proceed?
  • $${S_N}i$$
  • $${S_N}^{2}$$
  • $${S_N}^{1}$$
  • $$E_2$$
Assertion: $$E1cB$$ reaction is favoured by stabilisation of carbanion and poor leaving group
Reason: The reaction is kinetically of the second-order and unimolecular
  • Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
  • Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
  • Assertion is correct but Reason is incorrect
  • Assertion is incorrect but Reason is correct
  • Both Assertion and Reason are incorrect
Assertion: $$1^o$$ allylic halides are more reactive than $$1^oRX$$ in $$S_N1$$ reaction
Reason: Allylic carbocation intermediate is stabilised by resonance
  • Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
  • Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
  • Assertion is correct but Reason is incorrect
  • Assertion is incorrect but Reason is correct
  • Both Assertion and Reason are incorrect
Which of the following aromatic compound is least reactive towards electrophilic substitutions?
The first steps of $${SN}^{1}$$ and $${SN}^{2}$$ reactions are, respectively:
  • Both exothermic
  • Both endothermic
  • Endothermic and exothermic
  • Exothermic and endothermic
Which one of the following compounds gives $${S_N}{1}, {S_N}{2}$$ and $${S_N}{2'}$$ mechanisms?
Nitration of xylene gives only one mono-nitro derivative. Which xylene is it?
  • ortho
  • meta
  • para
  • Both o and p
During $$S_N1$$ reactions, the leaving group leaves the molecule before the incoming group is attached to the molecule
  • True
  • False
By which mechanism does the above reaction proceed?
253048_b1d38e25e9904a6a8c93a632b9e5d834.png
  • $$E_1$$
  • $$E_2$$
  • $$E_1cb$$
  • $$\gamma$$-Elimination
Which of the following represents Westrosol?
  • $$CH{Cl}_{3}$$
  • $${CH}_{2}{Cl}_{2}$$
  • $$CH{Cl}_{2}{CH}_{2}Cl$$
  • $$C{Cl}_{2}=CHCl$$
The chemical reaction:
$${ \left( { CH }_{ 3 } \right)  }_{ 3 } CBr \xrightarrow [ { -H }_{ 2 }O,-KBr ]{ KOH(alc.) }  { \left( { CH }_{ 3 } \right)  }_{ 2 }C={CH}_{2}$$ is an example of:
  • nucleophilic substitution
  • electrophilic substitution
  • free radical substitution
  • $$\beta$$-elimination
$${C}_{3}{H}_{7}Cl \xrightarrow [  ]{ KOH(alc.) }  (A) \xrightarrow [ 770K ]{ { Cl }_{ 2 }(g) }  (X)$$. $$(X)$$ can be:
  • vinyl chloirde
  • allyl chloride
  • ethyl chloride
  • ethyl iodide
Ethanol $$\xrightarrow [  ]{ { P }_{ 4 }/{ I }_{ 2 } }  (X) \xrightarrow [ (ii)HBr ]{ (i)KOH(alc.) }  (Y)$$
In this sequence of reaction , $$(Y)$$ is:
  • ethene
  • bromoethane
  • ethanol
  • none of these
$${C}_{6}{H}_{5}Cl \xrightarrow [ 625K, \ 300atm ]{ NaOH(aq.) } $$ 
The product can be:
  • benzal
  • sodium benzoate
  • benzol
  • sodium phenate
Which of the following is called Westron?
  • $${CH}_{3}Cl$$
  • $$CH{Cl}_{3}$$
  • $$CH{Cl}_{2}.CH{Cl}_{2}$$
  • $$C{Cl}_{2}=CHCl$$
$$(X)$$ on treatment with sodium hydroxide followed by the addition of silver nitrate gives white precipitate at room temperature which is soluble in $${NH}_{4}OH$$. $$(X)$$ can be:
  • chlorobenzene
  • ethyl bromide
  • benzyl chloride
  • vinyl chloride
Which of the following halides can yield ethane and also methane in a single step?
  • $${C}_{2}{H}_{5}Br$$
  • $${CH}_{3}I$$
  • $${ \left( { CH }_{ 3 } \right) }_{ 2 }CHBr$$
  • None
$${CH}_{3}-CH(Cl)-{C}_{2}{H}_{5} \xrightarrow [  ]{ Alc.\quad KOH }  {CH}_{3}-CH=CH-{CH}_{3}$$
The above reaction proceeds via $$E_1cb$$ mechanism?
  • It is second order and bumolecular
  • It is first order and unimolecular
  • It is first order an bimolecular
  • It is second order and unimolecular
The reaction of toluene with chlorine in the presence of ferric chloride gives predominantly:
  • Benzoyl chloride
  • $$m-chlorotoluene$$
  • Benzyl chloride
  • $$o-$$ and $$p-chlorotoluene$$
For the reaction, $$C_2H_5OH+HX\overset{ZnX_2}{\longrightarrow} C_2H_5X$$, the order of reactivity is:
  • $$\;HI>HCl>HBr$$
  • $$\;HI>HBr>HCl$$
  • $$HCl>HBr>HI$$
  • $$\;HBr>HI>HCl$$
Tertiary butyl chloride undergoes $$S_{N}1$$ reactions immediately .
  • True
  • False
Allyl chloride is a .............. compound while vinyl chloride is inert towards nucleophilic substitution.
  • reactive
  • mildly reactive
  • not reactive
  • netural
Aryl halides are less reactive towards nucleophilic substitution reaction as compared to alkyl halides due to:
  • the formation of less stable carbonium ion
  • resonance stabilisation
  • longer carbon-halogen bond
  • the inductive effect
  • $${sp}^{2}$$-hybridised carbon attached to the halogen
$$1,\:3$$- Dibromopropane reacts with metallic zinc to form:
  • propene
  • cyclopropane
  • propane
  • hexane
Vinyl chloride reacts with dilute $$NaOH$$ to form vinyl alcohol.
  • True
  • False
Secondary butyl chloride undergo alkaline hydrolysis in the polar solvent by ___________ mechanism.
  • $$\:S_{N}2$$
  • $$\;S_{N}1$$
  • $$\;S_{N}1$$ and $$S_{N}2$$
  • $$\;E\ 2$$
$$1-phenyl-2-chloropropane$$ on treating with alc. $$KOH$$ gives mainly:
  • $$1$$-phenylpropene
  • $$2$$-phenylpropene
  • $$1$$-phenylpropane-$$2$$-ol
  • $$1$$-phenylpropan-$$1$$-ol
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