Haloalkanes and Haloarenes VBQs Class 12 Chemistry

VBQs for Class 12

VBQs Haloalkanes and Haloarenes Class 12 Chemistry with Haloalkanes and Haloarenes has been provided below for standard students. We have provided chapter wise VBQ for Class 12 Chemistry with Haloalkanes and Haloarenes. The following Haloalkanes and Haloarenes Class 12 Chemistry value based questions with answers will come in your exams. Students should understand the concepts and learn the solved cased based VBQs provided below. This will help you to get better marks in class 12 examinations.

Haloalkanes and Haloarenes VBQs Class 12 Chemistry

Question. On sulphonation of C6H5Cl
(a) benzene sulphonic acid is formed
(b) metachlorobenzene sulphonic acid is formed
(c) orthochlorobenzene sulphonic acid is formed
(d) ortho and para chlorobenzene sulphonic acids are formed

Answer

D

Question. Which of the following is an optically active compound ?
(a) 1-Butanol
(b) 1-Propanol
(c) 2-Chlorobutane
(d) 4-Hydroxyheptane

Answer

C

Question. Which of the following compounds is used as a refrigerant?
(a) Acetone
(b) CCl4
(c) CF4
(d) CCl2F2

Answer

D

Question. Which of the following pairs of compounds are enantiomers?

Haloalkanes and Haloarenes VBQs Class 12 Chemistry
Answer

B

Question. Which of the following will have a mesoisomer also?
(a) 2, 3- Dichloropentane
(b) 2, 3-Dichlorobutane
(c) 2-Chlorobutane
(d) 2-Hydroxypropanoic acid

Answer

B

Question. Freon-12 is commonly used as
(a) insecticide
(b) refrigerant
(c) a solvent
(d) a fire extinguisher

Answer

B

Question. Optically active isomers but not mirror images are called
(a) enantiomers
(b) mesomers
(c) tautomers
(d) diastereomers

Answer

D

Question. An alkyl halide reacts with metallic sodium in dry ether. The reaction is known as :
(a) Frankland’s reaction
(b) Sandmeyer’s reaction
(c) Wurtz reaction
(d) Kolbe’s reaction

Answer

C

Question. Freon used as refrigerant is
(a) CF2 == CF2
(b) CH2F2
(c) CCl2F2
(d) CF4

Answer

C

Question. 2-Bromopentane is heated with potassium ethoxide in ethanol. The major product obtained is
(a) 2-ethoxypentane
(b) pentene-1
(c) trans-2-pentene
(d) cis-pentene-2

Answer

C

Question. An alkyl halide by formation of its Grignard reagent and heating with water yields propane. What is the original alkyl halide ?
(a) Methyl iodide
(b) Ethyl iodide
(c) Ethyl bromide
(d) Propyl bromide

Answer

D

Question. Solvent which is used in the synthesis of chlorofluorocarbons
(a) iodoform
(b) chloroform
(c) carbon tetrachloride
(d) methylene chloride

Answer

C

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. Which of following can be used as solvent for grignard reagent ?
(a) H2O
(b) C2H5OH
(c) CH3OH
(d) C2H5OC2H5

Answer

D

Question. Isobutyl magnesium bromide with dry ether and ethyl alcohol gives :

Haloalkanes and Haloarenes VBQs Class 12 Chemistry
Answer

B

Question. The reaction is described as

Haloalkanes and Haloarenes VBQs Class 12 Chemistry
Answer

C

Question. Benzene reacts with CH3Cl in the presence of anhydrous AlCl3 to form :
(a) chlorobenzene
(b) benzylchloride
(c) xylene
(d) toluene

Answer

D

Question. Which of the following is responsible for depletion of the ozone layer in the upper strata of the atmosphere?
(a) Polyhalogens
(b) Ferrocene
(c) Fullerenes
(d) Freons

Answer

D

Question. Chlorobenzene reacts with Mg in dry ether to give a compound (A) which further reacts with ethanol to yield
(a) Phenol
(b) Benzene
(c) Ethylbenzene
(d) Phenyl ether

Answer

B

Question. Which of the following is the correct order of decreasing SN2 reactivity?
(a) R2 C HX > R3CX > RCH2X
(b) RCHX > R3CX > R2CHX
(c) RCH2X > R2CHX > R3CX
(d) R3CX > R2CHX > RCH2X.
(X is a halogen)

Answer

C

Question.Benzene reacts with n-propyl chloride in the presence of anhydrous AlCl3 to give
(a) 3 – Propyl – 1 – chlorobenzene
(b) n-Propylbenzene
(c) No reaction
(d) Isopropylbenzene

Answer

D

Question. Which of the following is the example of Friedal Craft reaction?

Haloalkanes and Haloarenes VBQs Class 12 Chemistry
Haloalkanes and Haloarenes VBQs Class 12 Chemistry
Answer

C

Question. C – Cl bond of chlorobenzene in comparison to C – Cl bond in methyl chloride is
(a) Longer and weaker
(b) Shorter and weaker
(c) Shorter and stronger
(d) Longer and stronger

Answer

C

Question. An important chemical method to resolve a racemic mixture makes use of the formation of
(a) a meso compound
(b) enantiomers
(c) diasteromers
(d) racemates

Answer

C

Question. The process of separation of a racemic modification into d and l -enantiomers is called
(a) Resolution
(b) Dehydration
(c) Revolution
(d) Dehydrohalogenation

Answer

A

Question. Which one of the following is most reactive towards nucleophilic substitution reaction?
(a) CH= CH — Cl
(b) C6H5Cl
(c) CH3CH = CH — Cl
(d) ClCH2 — CH = CH2

Answer

D

Question. Which one is most reactive towards SN1reaction ?
(a) C6H5CH(C6H5)Br
(b) C6H5CH(CH3)Br
(c) C6H5C(CH3)(C6H5)Br
(d) C6H5CH2Br

Answer

C

Question. Which of the following alkyl halides is used as a methylating agent?
(a) C2H5Br
(b) C6H5Cl
(c) CH3I
(d) C2H5Cl

Answer

C

Question. Aryl halides can not be prepared by the reaction of aryl alcohols with PCl3, PCl5 or SOCl2 because
(a) phenols are highly stable compounds.
(b) carbon-oxygen bond in phenols has a partial double bond character.
(c) carbon-oxygen bond is highly polar
(d) all of these

Answer

B

Question. An organic molecule necessarily shows optical activity if it
(a) contains asymmetric carbon atoms
(b) is non-polar
(c) is non-superimposable on its mirror image
(d) is superimposable on its mirror image

Answer

C

STATEMENT TYPE QUESTIONS

Question. Read the following statements and choose the correct code
(i) SN2 reaction proceed with complete stereochemical inversion.
(ii) SN1 reaction proceed with recimisation.
(iii) A dextrorotatory compound rotate the plane polarised light to the left.
(iv) A laevorotatory compound rotate the plane polarised light to the right
(a) TFTT
(b) TTFF
(c) FFTT
(d) TFTF

Answer

B

Question. Following statements are given regarding the preparation of aryl halides from toluene. Read the following statements and choose the correct option.
(i) Aryl chlorides and bromides can be easily prepared by this method.
(ii) The ortho and para isomers formed in the reaction can not be separated easily due to small difference in their melting point.
(iii) Reactions with iodine are reversible in nature and require the presence of an oxidising agent.
(iv) Fluoro compounds are not prepared by this method due to low reactivity of fluorine.
(a) (i) and (iii) are correct
(b) (ii) and (iv) are correct
(c) (i), (ii), and (iii) are correct
(d) All statements are correct

Answer

A

Question. Which of the statement(s) is/are true, regarding following reaction?

Haloalkanes and Haloarenes VBQs Class 12 Chemistry

(i) The reaction involves the formation of transition state.
(ii) Higher the nucleophilic character of the nucleophile, faster will be the reaction.
(iii) The product is always optically inactive.
(a) (ii) only
(b) (ii) and (iii)
(c) (i), (ii) and (iii)
(d) Neither (i), (ii) nor (iii)

Answer

D

Question. Read the following statements and choose the correct answer
(i) The boiling points of isomeric haloalkanes decrease with increase in branching.
(ii) Among isomeric dihalobenzenes the para-isomers have higher melting point than their ortho and metaisomers.
(iii) The isomeric dihalobenzene have large difference in their boiling and melting points
(iv) The isomeric dihalobenzene have nearly same boiling point.
(a) (i), (ii) and (iii) are correct
(b) (i) and (iii) are correct
(c) (ii) and (iv) are correct
(d) (i), (ii) and (iv) are correct

Answer

D

Question.

Haloalkanes and Haloarenes VBQs Class 12 Chemistry

For the reaction scheme given above some statements are given. Read the statements and choose the correct option.
(i) If (A) is the only compound obtained, the process is called retention of configuration.
(ii) If (B) is the only compound obtained, the process is called inversion of configuration.
(iii) If a 50 : 50 mixture of the above two is obtained then the process is called racemisation
(iv) The product A + B is optically active
(a) TTTF
(b) TFTF
(c) TTFF
(d) TFFT

Answer

A

Question. Read the following statements and choose the correct option.
(i) The general formula of alkyl halides is CnH2n+1 X
(ii) The general formula of aryl halides is Cn Hn–1 X
(iii) In alkyl halides halogen atom(s) is attached to sp2 hybridised carbon atom
(iv) In aryl halides halogen atom(s) is attached to sp2 hybridised carbon atom.
(a) (i), (ii) and (iii) are correct
(b) (i), (ii) and (iv) are correct
(c) (ii), (iii) and (iv) are correct
(d) (i), (ii), (iii) and (iv) are correct

Answer

B

Question. Read the following statements and choose the correct option.
(i) SN1 reactions are carried out through formation of carbocation as an intermediate.
(ii) SN1 reactions are two step reactions in which step 1 is fast and irreversible.
(iii) Step 1 involves breaking of C–Br bond which obtain energy through solvation of halide.
(iv) SN1 reactions are two step reactions in which step 2 is slow and reversible.
(v) Allylic and benzylic halides show high reactivity toward SN1 reactions.
(a) (i), (iii) and (v) are correct
(b) (ii), (iii) and (v) are correct
(c) (i), (iii) and (iv) are correct
(d) (i), (ii) and (iv) are correct

Answer

A

Question. Read the following statements and choose the correct option.
(i) For the same alkyl group, the boiling points of alkyl halides decreases in the order.
RI > RBr > RCl > RF
(ii) With the increases in size and mass of halogen atom,the magnitude of van der Waal’s forces increases.
(a) Both statements (i) and (ii) are correct
(b) Statement (i) is correct and (ii) is incorrect
(c) Statement (ii) is correct and (i) is incorrect
(d) Both statement (i) and (ii) are incorrect

Answer

A

MATCHING TYPE QUESTIONS

Question. Match the columns

Haloalkanes and Haloarenes VBQs Class 12 Chemistry

(a) A – (q), B – (s), C – (p), D – (r)
(b) A – (q), B – (r), C – (p), D – (s)
(c) A – (r), B – (p), C – (s), D – (q)
(d) A – (s), B – (r), C – (p), D – (q)

Answer

A

Question. Match the columns
Column-I                                Column-II
(A) Chloramphenicol               (p) Goiter
(B) Thyroxine                        (q) Surgery
(C) Chloroquine                     (r) Typhoid
(D) Halothane                        (s) Malaria
(a) A – (q), B – (p), C – (s), D – (r)
(b) A – (r), B – (p), C – (s), D – (q)
(c) A – (s), B – (r), C – (q), D – (p)
(d) A – (p), B – (s), C – (q), D – (r)

Answer

B

Question. Match the columns.
Column – I                      Column – II
(Haloalkane/arene)      (Applications)
(A) Iodoform                  (p) CF4
(B) BHC                         (q) Antiseptic
(C) Freon – 14                (r) Moth repellant
(D) Halothanes               (s) Inhalative anesthetic
(E) p-dichlorobenzene     (t) Termite pesticide
(a) A – (q), B – (s), C – (t), D – (r), E – (p)
(b) A – (q), B – (t), C – (p), D – (s), E – (r)
(c) A – (r), B – (s), C – (q), D – (p), E – (t)
(d) A – (p), B – (r), C – (t), D – (q), E – (s)

Answer

B

Question. Match the columns
Column – I                             Column – II
(A) CH2 = CH – CH2Cl          (p) Gem-dichloride
(B) CH2 = CHX                    (q) Vinylic halide
(C) CH3CHCl2                      (r) Dichloride
(D) CH2Cl CH2Cl                 (s) Allylic halide
(a) A – (r), B – (q), C – (p), D – (s)
(b) A – (q), B – (p), C – (s), D – (r)
(c) A – (s), B – (q), C – (p), D – (r)
(d) A – (r), B – (p), C – (s), D – (q)

Answer

C

Question. Match the columns
Column – I                      Column – II
(A) Chloroform              (p) Antiseptic
(B) Iodoform                 (q) Insecticide
(C) Trichloromethane     (r) Anesthetic
(D) DDT                       (s) Propellant
(a) A – (s), B – (p), C – (r), D – (q)
(b) A – (r), B – (p), C – (s), D – (q)
(c) A – (q), B – (s), C – (p), D – (q)
(d) A – (r), B – (s), C – (p), D – (q)

Answer

B

ASSERTION-REASON TYPE QUESTIONS

Directions : Each of these questions contain two statements,Assertion and Reason. Each of these questions also has four alternative choices, only one of which is the correct answer. You have to select one of the codes (a), (b), (c) and (d) given below.
(a) Assertion is correct, reason is correct; reason is a correct explanation for assertion.
(b) Assertion is correct, reason is correct; reason is not a correct explanation for assertion
(c) Assertion is correct, reason is incorrect
(d) Assertion is incorrect, reason is correct.

Question. Assertion : Alkylbenzene is not prepared by Friedel-Crafts alkylation of benzene.
Reason : Alkyl halides are less reactive than acyl halides.

Answer

C

Question. Assertion : SN2 reaction of an optically active aryl halide with an aqueous solution of KOH always gives an alcohol with opposite sign of rotation.
Reason : SN2 reactions always proceed with inversion of configuration.

Answer

D

Question. Assertion : CCl4 is not a fire extinguisher.
Reason : CCl4 is insoluble in water.

Answer

D

Question. Assertion : CHCl3 is stored in dark bottles.
Reason : CHCl3 is oxidised in dark.

Answer

C

Question. Assertion : Exposure of ultraviolet rays to human causes the skin cancer, disorder and disrupt the immune system.
Reason : Carbon tetrachloride is released into air it rises to atmosphere and deplets the ozone layer.

Answer

B