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

Following is an example of an E2 reaction.

258482.png
  • True
  • False
Consider the following anions.
When attached to $$sp^{3-}$$ hybridized carbon, their leaving group ability in nucleophilic substitution reactions decreases in the order.
262909_69d1f175b4684b20bb228ca0ec891cc5.png
  • $$\;I>II>III>IV$$
  • $$\;I>II>IV>III$$
  • $$\;IV>I>II>III$$
  • $$\;IV>III>II>I$$
Allyl chloride is more reactive than vinyl chloride.
  • True
  • False
When phenol is treated with excess bromine water, it gives:
  • m-Bromophenol
  • o- and p-Bromophenol
  • 2,4-Dibromophenol
  • 2,4,6-Tribromophenol
Arrange the following in the increasing order of their ability as a leaving group: $$CF_3SO_3^-,\,CH_3SO_3^-\,and\,CH_3COO^-$$
  • $$ CH_3SO_3^- $$ > $$CF_3SO_3^-$$ > $$ CH_3COO^-$$
  • $$CF_3SO_3^-$$ > $$ CH_3SO_3^- $$ > $$ CH_3COO^-$$
  • $$CF_3SO_3^-$$ > $$ CH_3COO^-$$ > $$ CH_3SO_3^- $$
  • $$CF_3SO_3^-$$ < $$ CH_3SO_3^- $$ < $$ CH_3COO^-$$
Which of the following products will be obtained when neopentyl alcohol is treated with conc. $$HCl$$ in presence of $$Zn{Cl}_{2}?$$
  • t-Butyl chloride
  • Isobutylene
  • t-Pentyl chloride
  • Neo pentyl chloride
Which of the following order is correct for the decreasing reactivity of ring monobromination of the following compounds?
274369.bmp
  • $$I > II > III > IV$$
  • $$II > III > IV > I$$
  • $$I > III > II > IV$$
  • $$III > I > II > IV$$
Which of the following compounds will give $$S_{N}1$$ and $$S_{N}2$$ reactions with considerable rate?
I.$$\;C_6H_5-CH_2-Br$$
II.$$\;CH_2=CH-CH_2-Br$$
III.$$\,CH_3-CH(Br)CH_3$$
Select the correct answer from the codes below below.
263515.bmp
  • $$\;I,\,II\,and\,III$$
  • $$\;I,\,II\,and\,IV$$
  • $$\;II,\,III\,and\,IV$$
  • $$\;I,\,III\,and\,IV$$
What will be the product of the following the reaction 
           $$\underset{|}{CH_3}$$
$$CH_3-C-CH_2-Br\xrightarrow[]{NaOH} P$$,  
          $$\overset{|}{CH_3}$$

P is ________.
  • $$CH_3-C\! \! \! =CH-CH_3$$
    $$\; \; \; \; \; \; \; \; \; \overset{|}{CH_3}$$
  • $$CH_3-CH-CH=CH_2$$
    $$\; \; \; \; \; \; \; \; \; \overset{|}{CH_3}$$
  • Both of these
  • None of these
cis-2-butene $$\underset{CCl_4}{\xrightarrow{Br_2}}$$ $$P$$
$$(P)$$ is:
  • Both $$A$$ and $$B$$
Find the major product of the following reaction.
295651_3176f4bff52a4f90880405f37aa127f6.png
  • none
An organic compound $$A(C_4H_9Cl)$$ on reaction with $$Na/diethyl \hspace{1mm}ether$$ gives a hydrocarbon which on monochlorination gives only one chloro derivative. $$A$$ is:
  • t-butyl chloride
  • sec-butyl chloride
  • isobutyl chloride
  • n-butyl chloride
A mixture of two organic compounds was treated with sodium metal in ether solution. Isobutane was obtained as a product. The two chlorine compounds are:
  • methyl chloride and propyl chloride
  • methyl chloride and ethyl chloride
  • isopropyl chloride and Methyl chloride
  • isopropyl chloride and ethyl chloride
Product formed in the reaction is__________.
295650.png
Under identical conditions, solvolysis of which of the following substrates would lead to maximum racemization?
For the following reaction which of the following statement is/are correct?
432689_21a28ef2bcc841608c5e21c97ab9dc92.png
  • Both $$X$$ and $$Y$$ are five membered cyclic ring
  • Reaction (i) follows $$E2$$ path where as reaction (ii) follows $$E1$$ path
  • Reaction (ii) has carbocation as an intermediate
  • Carbocation rearrangemnet takes place in reaction (i)
Which of the following applies in the reaction?

$${ CH }_{ 3 }CH(Br){ CH }_{ 2 }{ CH }_{ 3 }\xrightarrow [  ]{ Alc.KOH }$$ ?

(I) $${ CH }_{ 3 }CH=CH-{ CH }_{ 3 }$$ (major product)
(II) $${ CH }_{ 2 }=CH{ CH }_{ 2 }{ CH }_{ 3 }$$ (minor product)
  • Hofmann's rule
  • Saytzeff's rule
  • Kharasch effect
  • Markovnikov’s rule
Alkyl halides and alcohols easily undergo nucleophilic substitution either through $$S_N1$$ or $$S_N2$$ mechanism. The relative case of these two processes depends upon the nature of the substrate (alkyl group) as well as leaving group, nature of nucleophile and also upon the nature of the solvent.
           $$S_N1$$ mechanism involves the formation of carbocation as intermediate while $$S_N2$$ mechanism involves the formation of a transition pentavalent state. $$S_N1$$ is the main mechanism in $$3^0$$ alkyl halides and alcohols, while $$S_N2$$ mechanism is the path adopted by most of the $$1^o$$ alkly halides; $$2^o$$ alkyl halides may follow $$S_N1$$ as well as $$S_N2$$.

What happens when $$1^o ROH$$ react with $$HX$$?
  • The $$1^o$$ carbocations are unstable and hence are not formed.
  • The carbocations are unstable and hence undergo rearrangement.
  • The $$1^o$$ alcohol forms protonated alcohol and then follow $$S_N2$$ path.
  • $$X^-$$ makes an $$S_N2$$ attack at $$\alpha - C$$ in $$1^oROH$$.

$$\xrightarrow{1eqv.\,

of Br_2 / Fe}$$ A. Compound A is:
305135_b10225102dd249eb810401136aca723d.png
Which one of the following compounds will be most readily dehydrated? 
The major product is:
332681_5af816cddeb74d76acd9465cd0570df9.png
  • None of these
Which of the following solvent will give maximum yield for an alkyl halide undergoing $$S_N1$$ mechanism?
  • Water
  • Ethanol
  • Diethyl ether
  • n-hexane
Which of the following cannot undergo nucleophilic substitution under ordinary conditions?
  • Chlorobenzene
  • Tert-butyl chloride
  • Iso-propyl chloride
  • None of the above
In the above reactions, which of the following is/ are products?

551525.png
  • $$1,2$$- Dichlorobenzene
  • $$1,3$$- Dichlorobenzene
  • $$1,4$$- Dichlorobenzene
  • Both A and C
An organic compound which produces a bluish-green coloured flame on heating in presence of copper is:
  • chlorobenzene
  • benzaldehyde
  • anlline
  • benzoic acid
On treating a mixture of two alkyl halides with sodium metal in dry ether, $$2-$$ methyl propane was obtained. The alkyl halides are:
  • $$2$$- chloropropane and chloromethane
  • $$2$$- chloropropane and chloroethane
  • chloromethane and chloroethane
  • chloromethane and $$1$$- chloropropane
Haloarenes react with halogens in the presence of ferric salt as catalyst to give ortho and para dichloro benzene. Which of the following products predominates in ortho and para isomers in this case?
  • Ortho-dichlorobenzene
  • Para-dichlorobenzene
  • Meta-dichlorobenzene
  • A and C both
Which of the following is the best method for synthesis of 1-bromo-3-chlorobenzene?
The reaction of 1-bromo-3-chlorocyclobutane with metallic sodium in dioxane under reflux condition gives:
In the following reaction, identify the product.
639705_4a4d3af015944753922d325d3a22e1d3.png
  • $$\underset{\,\,\,OH}{\underset{|}{C}}\!\!\!H_2-\underset{CH_3}{\underset{|}{C}H}-C_2H_5$$
  • $$C_2H_5-\underset{OH}{\underset{|}{C}H}-CH_2CH_3$$
  • $$C_2H_5-CH_2-\!\!\underset{\,\,OH}{\underset{|}{C}}\!\!H - CH_3$$
  • $$C_2H_5-CH = CH - CH_3$$
Bromo ethane and isoproply chloride with metallic sodium in ether forms :
  • Pentane
  • 2-methyl butane
  • 3-methyl butane
  • 2:3 dimethyl butane
$$C_7H_8\overset{3Cl_2/ heat}{\rightarrow}A\overset{Fe/Br}{\rightarrow}B\overset{Zn/HCl}{\rightarrow}C$$. Here, the compound C is:
  • $$3$$-bromo $$2,4,6$$-trichlorotoluene
  • o-bromotoluene
  • P-bromotoluene
  • m-bromotoluene
Anisole can be prepared by the action of methyl iodide on sodium phenate. The reaction is called:
  • Wurtz reaction
  • Williamson's reaction
  • Fittig's reaction
  • Etard's reaction
Wurtz reactions have low yield because of ___________
  • the formation of multiple products.
  • reaction is reversible
  • reagent used are impure
  • none of these
In electrophilic aromatic substitution reactions of chlorobenzene, the ortho/para-directing ability of chlorine is due to its _______.
  • positive inductive effect $$(+I)$$
  • negative inductive effect $$(-I)$$
  • positive resonance effect $$(+R)$$
  • negative resonance effect $$(-R)$$
The order of rate of $$S_N1$$ in following iodo compounds is:
791721_1a6993cb278e4374991db3e6b7d08d83.png
  • I > II > III
  • I > III > II
  • III > II > I
  • II > III > I
$$A$$ and $$B$$ are:
792457_ba1e104fb0ed415e83535900112df59b.png
  • none of these
Which of  the following reactions is not correctly matched?
  • $$2C_2H_5Br +2Na\xrightarrow{dry\ ether}C_4H_{10}+2NaBr$$

    Wurtz reaction
  • $$CH_3Br+AgF\rightarrow CH_3F +AgBr$$

    Etards reaction
  • $$C_6H_5Br +2Na+BrC_2H_5\xrightarrow{dry\ ether}C_6H_5C_2H_5+2NaBr$$

    Wurtz-fittig reaction
  • $$2C_6H_5Br +2Na\xrightarrow{dry\ ether}C_6H_5C_6H_5+2NaBr$$

    Fittig reaction
The antiaromatic compounds are:
874493_03579bb53f9246bcb9a4762276be276f.png
  • $$x,w$$
  • $$y,z$$
  • $$x,z$$
  • $$y,w$$
Arrange the following alkyl halides in decreasing order of the rate of $$\beta$$-elimination reaction with alcoholic $$KOH$$. 
(I) $$ CH_{ 3 }-\overset { \overset { H }{ | }  }{ \underset { \underset { CH_{ 3 } }{ | }  }{ C }  } -CH_{ 2 }Br$$
(II) $$CH_3-CH_2-Br$$
(III)  $$CH_3-CH_2-CH_2-Br$$
  • $$I > II > III$$
  • $$III > II > I$$
  • $$II > III > I$$
  • $$I > III > II$$
The major product(s) obtained in the following reaction is/are.
876865_429a33df96c340f58bd43fb55c62dee3.png
$$\xrightarrow [ 2Na ]{

dry\ ether }$$
864557_449b0ee5c64840efbb52a7aad16eefa7.png
Which of alkyl halides exhibits complete racemisation in $$S_N1$$ reaction?
  • $$(CH)_3CCl$$
  • $$CH_3CH_2CH_2Cl$$
  • $$CH_3CH_2Cl$$
  • $$C_6H_5CH_2Cl$$
Which of the following alkane cannot be prepared by Wurtz's reaction in good yield?
Match the column I with column II.
Columns I Columns II 
ACarbon tetrachloride iPaint remover 
BMethylene chloride iiRefrigerators and air conditioners 
CDDTiiiFire extinguisher 
DFreonsivNon biodegradable insectiside 
  • A-(ii), (B)-(iii), (C)-(i), (D)-(iv)
  • A-(i), (B)-(ii), (C)-(iii), (D)-(iv)
  • A-(iv), (B)-(iii), (C)-(ii), (D)-(i)
  • A-(iii), (B)-(i), (C)-(iv), (D)-(ii)
What is the product of given reaction?
877649_dd8ec8f9856e48fdabfe8c9fe278f637.png
Which of the following order is/are correct for the solvolysis in $$50\%$$ aqueous ethanol at $$44.6^oC$$?
The major product obtained on treatment of $$ \mathrm { CH } _ { 3 } \mathrm { CH } _ { 2 } \mathrm { CH } ( \mathrm { F } ) \mathrm { CH } _ { 3 } $$ with $$ \mathrm { CH } _ { 3 } \mathrm { O } ^{- }/ \mathrm { CH } _ { 3 } \mathrm { OH } $$ is 
  • $$ \mathrm { CH } _ { 3 } \mathrm { CH } _ { 2 } \mathrm { CH } \left( \mathrm { OCH } _ { 3 } \right) \mathrm { CH } _ { 3 } $$
  • $$ \mathrm { CH } _ { 3 } \mathrm { CH } = \mathrm { CHCH } _ { 3 } $$
  • $$ \mathrm { CH } _ { 3 } \mathrm { CH } _ { 2 } \mathrm { CH } = \mathrm { CH } _ { 2 } $$
  • $$ \mathrm { CH } _ { 3 } \mathrm { CH } _ { 2 } \mathrm { CH } _ { 2 } \mathrm { CH } _ { 2 } \mathrm { OCH } _ { 3 } $$
Which of the following does not represent major product of that reaction?
Which of the following biphenyl compound is not optically active?
  • Both $$(B)$$ and $$(C)$$
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