NEET Chemistry Haloalkanes and Haloarenes MCQs Set B

Question: Which of the following is least reactive towards nucleophilic substitution?

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question:  Among the following

The correct order of reactivity towards ArSN mechanism is

• a) I > III > II > IV
• b) I > II > IV > III
• c) III > II > IV > I
• d) I > IV > II > III

Answer: I > IV > II > III

Question:  Which of the following does not give yellow precipitate with AgNO₃?

• a) (CH₃)₃C—CH₂—I
• b) CH₂==CH—CH₂—I
• c)

  

• d)

  

Answer:

Question:

What is C?

• a) CH₃–CH₃
• b)

  

• c)

  

• d) CH₂= CH₂

Answer:  CH₃–CH₃

Question:

The product (C) is

• a)

  

• b)

  

• c)

  

• d) Mixture of (1) & (2)

Answer: Mixture of (1) & (2)

Question:  In the given reaction

The product will be

• a) Cis-2-butene
• b) Trans-2-butene
• c) 2-butyne
• d) Buta-1, 3-diene

Answer: Trans-2-butene

Question: Under identical conditions, solvolysis of which of the following substrate would lead to maximum racemisation?

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question:  The correct orders of reactivity towards S_N1 reaction is

• a) I > II > III
• b) II > III > I
• c) III > II > I
• d) I > III > II

Answer: II > III > I

Question:  When cis-but-2-ene is treated with Br₂ in CCl₄ medium the product formed will be 

• a) (2R, 3S) dibromobutane
• b) (2R, 3R) dibromobutane
• c) (2S, 3S) dibromobutane
• d) Mixture of (2R, 3R) and (2S, 3S) dibromobutane

Answer: Mixture of (2R, 3R) and (2S, 3S) dibromobutane

Question:

Above equilibrium is more towards right because

• a) NaI is more reactive than NaCl
• b) CH₃I is more reactive than CH₃Cl
• c) NaCl is less soluble than NaI in acetone
• d) It is Finkelstein’s reaction

Answer: NaCl is less soluble than NaI in acetone

Question:   Two possible stereo-structures of CH₃CHOH.COOH, which are optically active, are called 

• a) Enantiomers
• b) Mesomers
• c) Diastereomers
• d) Atropisomers

Answer: Enantiomers

Question:  In an S_N1 reaction on chiral centres, there is 

• a) 100% retention
• b) 100% inversion
• c) 100% racemization
• d) Inversion more than retention leading to partial racemization

Answer: Inversion more than retention leading to partial racemization

Question:   In which of the following compounds, the C – Cl bond ionisation shall give most stable carbonium ion?

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question:   What products are formed when the following compound is treated with Br₂ in the presence of FeBr₃?

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question:   Which of the following compounds will undergo racemisation when solution of KOH hydrolyses ?

• a) (i) and (ii)
• b) (ii) and (iv)
• c) (iii) and (iv)
• d) (i) and (iv)

Answer: (i) and (iv)

Question:  In the replacement reaction

The reaction will be most favourable if M happens to be

• a) Na
• b) K
• c) Rb
• d) Li

Answer: Li

Question: Which of the following compounds undergoes nucleophilic substitution reaction most easily ?

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question:  Consider the reactions

The mechanisms of reactions (i) and (ii) are respectively

• a) S_N2 and S_N2 
• b) S_N2 and S_N1
• c) S_N1 and S_N2  
• d) S_N1 and S_N1

Answer: S_N2 and S_N2 

Question:  The correct order of increasing reactivity of C–X bond towards nucleophile in the following compound is

• a) I < II < IV < III
• b) II < III < I < IV
• c) IV < III < I < II
• d) III < II < I < IV

Answer: I < II < IV < III

Question:  Which one is most reactive towards S_N1 reaction ? 

• a) C₆H₅CH(C₆H₅)Br  
• b) C₆H₅CH(CH₃)Br
• c) C₆H₅C(CH₃) (C₆H₅)Br 
• d) C₆H₅CH₂Br

Answer: C₆H₅C(CH₃) (C₆H₅)Br 

More Questions............................................

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:  RX + KOH →ROH + KX

Question:

A (predominantly) is

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question:  In a S_N2 substitution reaction of the type

Which one of the following has the highest relative rate?

• a) CH₃CH₂Br  
• b) CH₃–CH₂–CH₂Br
• c)

  

• d)

  

Answer: CH₃CH₂Br  

Question: If there is no rotation of plane polarized light by a compound in a specific solvent, thought to be chiral, it may mean that

• a) The compound may be a racemic mixture
• b) The compound is certainly a chiral
• c) The compound is certainly meso
• d) There is no compound in the solvent

Answer: The compound is certainly meso

Question:  Which of the following undergoes nucleophilic substitution exclusively by S_N1 mechanism ?

• a) Benzyl chloride
• b) Ethyl chloride
• c) Chlorobenzene
• d) Isopropyl chloride

Answer: Benzyl chloride

Question:  The chirality of the compound

is

• a) R
• b) S
• c) Z
• d) E

Answer: R

Question:  For the following

a. I^–

b. Cl^–

c. Br^–

The increasing order of nucleophilicity would be 

• a) Br^– < Cl^– < I^– 
• b) I^– < Br^– < Cl^–   
• c) Cl^– < Br^– < l^–  
• d) I^– < Cl^– < Br^–

Answer:  Cl^– < Br^– < l^–  

Question:

‘C’ has the formula C₅H₁₂  which can give four isomeric monochloro derivative. What is the structure of C₅H₁₁Br?

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question:   CD₂= CH – CH₂– Br is subjected to S_N1 and S_N2 reactions separately, which of the following statement is correct?

• a) Both S_N1 and S_N2 give two products
• b) Both S_N1 and S_N2 give only one product
• c) S_N1 gives two products but S_N2 gives only one product 
• d) S_N1 gives one product but S_N2 gives two products

Answer:  S_N1 gives two products but S_N2 gives only one product 

Question:   In the following reaction,

the product 'X' is

• a) C₆H₅CH₂OCH₂C₆H₅
• b) C₆H₅CH₂OH  
• c) C₆H₅CH₃ 
• d) C₆H₅CH₂CH₂C₆H₅

Answer:  C₆H₅CH₃ 

Question: In Finkelstein reaction when acetone is replaced by water then

• a) Reaction occurs in forward direction via S_N1 pathway
• b) Reaction occurs in forward direction via S_N2 pathway
• c) Reaction occurs in backward because NaCl formed in right hand side is soluble in water and cannot ppt.out
• d) Reaction is not possible

Answer: Reaction occurs in backward because NaCl formed in right hand side is soluble in water and cannot ppt.out

Question: Which graph is incorrect?

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question:  Which will undergo fastest S_N2 substitution reaction when treated with NaOH?

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question:  Given reaction

Y in the reaction is

• a) Hexane
• b) Cyclohexane
• c) Cyclohexylcyclohexane
• d) Cyclohexyl ether

Answer: Cyclohexane

Question: Which one of the following alkyl bromides undergoes most rapid solvolysis in methanol solution to give corresponding methyl ether?

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question: Grignard reagent is prepared by the reaction between

• a) Magnesium and alkane
• b) Magnesium and aromatic hydrocarbon
• c) Zinc and alkyl halide
• d) Magnesium and alkyl halide

Answer: Magnesium and alkyl halide

Question: Monobromination of 2-methylbutane gives how many distinct structural isomers?

• a) One
• b) Two
• c) Three
• d) Four

Answer: Four

Question:  The following reaction is described as

• a) S_N2   
• b) S_N0
• c) S_E2   
• d) S_N1

Answer:  S_N2   

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

• a) trans-pentene-2
• b) Pentene-1
• c) 2-ethoxypentane
• d) cis-pentene-2

Answer: trans-pentene-2

Question: Reactivity order of halides for dehydrohalogenation is

• a) R – F > R – Cl > R – Br > R – I
• b) R – I > R – Br > R – Cl > R – F
• c) R – I > R – Cl > R – Br > R – F 
• d) R – F > R – l > R – Br > R – Cl

Answer: R – I > R – Br > R – Cl > R – F

Question: Which of the following is not chiral

• a) 2-hydroxypropanoic acid
• b) 2-butanol
• c) 2,3-dibromopentane
• d) 3-bromopentane

Answer: 3-bromopentane

Question:  An organic compound A(C₄H₉Cl) on reaction with Na/diethyl ether gives a hydrocarbon which on monochlorination gives only one chloro derivative then, A is

• a) t-butyl chloride
• b) Secondary butyl chloride
• c) Isobutyl chloride
• d) n-butyl chloride

Answer: t-butyl chloride

Question: Which of the following compounds is not chiral?

• a) CH₃CHDCH₂Cl  
• b) CH₃CH₂CHDCl
• c) DCH₂CH₂CH₂Cl   
• d) CH₃CHClCH₂D

Answer:  DCH₂CH₂CH₂Cl   

Question: Which of the following is a secondary alkyl halide?

• a) Isobutyl chloride
• b) Isopentyl chloride
• c) Neopentyl chloride
• d) Isopropyl chloride

Answer: Isopropyl chloride

Question:  Which of the following solvent is suitable for S_N1 reaction?

• a) Non-polar
• b) Polar protic
• c) Polar aprotic
• d) All of these

Answer: Polar protic

Question: Chloropicrin is obtained by the reaction of

• a) Steam on carbon tetrachloride
• b) Nitric acid on chlorobenzene
• c) Chlorine on pricric acid
• d) Nitric acid on chloroform

Answer: Nitric acid on chloroform

Question: Which of the following is least reactive in a nucleophilic substitution reaction?

• a) (CH₃)₃C – Cl 
• b) CH₂= CHCl 
• c) CH₃CH₂Cl  
• d) CH₂= CHCH₂Cl

Answer: CH₂= CHCl 

Question: Ethylidene chloride reacts with aq. KOH to form which of the following compound?

• a) Acetaldehyde
• b) Ethylene glycol
• c) Ethyl alcohol
• d) Acetic acid

Answer: Acetaldehyde

Question: Grignard reagent is prepared by the reaction between

• a) Magnesium and alkane
• b) Magnesium and aromatic hydrocarbon
• c) Zinc and alkyl halide
• d) Magnesium and alkyl halide

Answer: Magnesium and alkyl halide

Question: Chloropicrin is obtained by the reaction of

• a) Steam on carbon tetrachloride
• b) Nitric acid on chlorobenzene
• c) Chlorine on pricric acid
• d) Nitric acid on chloroform

Answer: Nitric acid on chloroform

Question:

The major product ‘P’ is

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question: Which of the following is not chiral?

• a) 2-hydroxypropanoic acid
• b) 2-butanol
• c) 2,3-dibromopentane
• d) 3-bromopentane

Answer: 3-bromopentane

Question: Which of the following is least reactive in a nucleophilic substitution reaction?

• a) (CH₃)₃C – Cl 
• b) CH₂= CHCl
• c) CH₃CH₂Cl  
• d) CH₂= CHCH₂Cl

Answer:  CH₂= CHCl

Question: Which of the following compounds is not chiral?

• a) CH₃CHDCH₂Cl 
• b) CH₃CH₂CHDCl
• c) DCH₂CH₂CH₂Cl 
• d) CH₃CHClCH₂D

Answer: DCH₂CH₂CH₂Cl 

Question: Monobromination of 2-methylbutane gives how many distinct structural isomers?

• a) One
• b) Two
• c) Three
• d) Four

Answer: Four

Question:  Two possible stereo-structures of CH₃CHOH.COOH, which are optically active, are called 

• a) Enantiomers
• b) Mesomers
• c) Diastereomers
• d) Atropisomers

Answer: Enantiomers

Question:

Above equilibrium is more towards right because

• a) NaI is more reactive than NaCl
• b) CH₃I is more reactive than CH₃Cl
• c) NaCl is less soluble than NaI in acetone
• d) It is Finkelstein’s reaction

Answer: NaCl is less soluble than NaI in acetone

Question:  In the given reaction

The product will be

• a) Cis-2-butene
• b) Trans-2-butene
• c) 2-butyne
• d) Buta-1, 3-diene

Answer:  Trans-2-butene

Question:

What is C? 

• a) CH₃–CH₃
• b)

  

• c)

  

• d) CH₂= CH₂

Answer:  CH₃–CH₃

Question: Chloropicrin is obtained by the reaction of

• a) Steam on carbon tetrachloride
• b) Nitric acid on chlorobenzene
• c) Chlorine on pricric acid
• d) Nitric acid on chloroform

Answer: Nitric acid on chloroform