Haloalkanes and Haloarenes HOTs Class 12 Chemistry

Please refer to Haloalkanes and Haloarenes HOTs Class 12 Chemistry provided below with solutions. All HOTs for Class 12 Chemistry with answers provided below have been designed as per the latest syllabus and examination petter issued by CBSE, NCERT, KVS. Students of Standard 12 Chemistry should learn the solved HOTS for Class 12 Chemistry provided below to gain better marks in examinations.

Haloalkanes and Haloarenes Class 12 Chemistry HOTs

CRITICAL THINKING TYPE QUESTIONS 

Question. Which of the following statements is correct?
(a) S_N2 reactions of optically active halides are accompanied by inversion of configuration.
(b) S_N1 reactions of optically active halides are accompanied by racemisation.
(c) Carbocation formed in S_N1 reaction is sp² hybridized.
(d) All of the above. 

Question. A compound is formed by substitution of two chlorine for two hydrogens in propane. The number of possible isomeric compounds is
(a) 4
(b) 3
(c) 5
(d) 2

Question. A set of compounds in which the reactivity of halogen atom in the ascending order is
(a) chlorobenzene, vinyl chloride, chloroethane
(b) chloroethane, chlorobenzene, vinyl chloride
(c) vinyl chloride, chlorobenzene, chloroethane
(d) vinyl chloride, chloroethane, chlorobenzene 

Question. The catalyst used in the preparation of an alkyl chloride by the action of dry HCl on an alcohol is
(a) Anhydrous AlCl₃
(b) FeCl₃
(c) Anhydrous ZnCl₂
(d) Cu

Question. Which chloride is least reactive with the hydrolysis point of view?
(a) CH₃Cl
(b) CH₃CH₂Cl
(c) (CH₃)₃CCl
(d) CH₂ = CH – Cl 

Question. Which one of the following has antiseptic property?
(a) Dichloromethane
(b) Trifluoromethane
(c) Triiodomethane
(d) Tetrachloromethane 

Question. The number of structural and configurational isomers of a bromo compound, C₅H₉Br, formed by the addition of HBr to 2-pentyne respectively are
(a) 1 and 2
(b) 2 and 4
(c) 4 and 2
(d) 2 and 1

Question. Chronic chloroform exposure may cause damage to liver and kidney, due to the formation of
(a) phosgene
(b) methylene chloride
(c) methyl chloride
(d) carbon tetrachloride

Question. Which of the following reagent produces pure alkyl halides when heated with alcohols?
(a) PCl₅
(b) PCl₃
(c) SOCl₂
(d) dry HCl

Question. In a S_N2 substitution reaction of the type

Question. The spatial arrangement of four groups around a central carbon atom is tetrahedral and if all the substituents attached to that a carbon are different. Such a carbon is called ______.
(a) asymmetric carbon
(b) stereocentre
(c) chiral
(d) All of these 

Question. Fluorobenzene (C₆H₅F) can be synthesized in the laboratory
(a) by direct fluorination of benzene with F₂ gas
(b) by reacting bromobenzene with NaF solution
(c) by heating phenol with HF and KF
(d) from aniline by diazotisation followed by heating the diazonium salt with HBF₄ 

Question. Which one of the following is not an allylic halide?
(a) 4-Bromopent-2-ene
(b) 3-Bromo-2-methylbut-1-ene
(c) 1-Bromobut-2-ene
(d) 4-Bromobut-1-ene 

Question. Natural ozone layer is unbalanced due to
(a) cloudiness of poisonous gases
(b) presence of rain in the atmosphere
(c) initiation of radical chain by freon
(d) All of the above 

Question. Consider the following bromides :

The correct order of S_N1 reactivity is
(a) B > C > A
(b) B > A > C
(c) C > B > A
(d) A > B > C

Question. In which part of the atmosphere, does the freon remain unchanged ?
(a) Stratosphere
(b) Troposphere
(c) Mesosphere
(d) Thermosphere

Question. Which one is most reactive towards SN1 reaction ?
(a) C₆H₅CH(C₆H₅ )Br
(b) C₆H₅CH(CH₃)Br
(c) C₆H₅C(CH₃)(C₆H₅)Br
(d) C₆H₅CH₂Br 

Question. The number of possible enantiomeric pairs that can be produced during monochlorination of 2-methylbutane is
(a) 2
(b) 3
(c) 4
(d) 1

Question. The organic chloro compound, which shows complete stereochemical inversion during a S_N2 reaction, is
(a) (C₂H₅)₂CHCl
(b) (CH₃)₃CCl
(c) (CH₃)₂ CHCl
(d) CH₃Cl

Question. Under certain conditions an alkyl halide reacts with base to give an alkene and HCl [Elimination Reaction] for example
R – CH₂ – CH₂ – Cl → R – CH = CH₂ + HCl
The extent of these reactions depends on the structure of alkyl halides (e.g. primary, secondary or tertiary). The relative extent to which such reactions take place is in the order
(of haloalkanes) :
(a) Primary < secondary < Tertiary
(b) Primary > Secondary > Tertiary
(c) Primary > Secondary < Tertiary
(d) Primary < Secondary > Tertiary 

Question. Possible major product formed in the reaction of neopentylalcohol with HCl is
(a) 2 -chloro-2-methylbutane
(b) 2, 2 -dimethyl 1-chloropropane
(c) 2 -chloro -3-methylbutane
(d) 3, chloro -3-methylbutane

Question. Which of the following represents correct set of ambident nucleophiles?
(a) CN^– and NH₃
(b) CN^–, NO₂
(c) OH^–, RO^–
(d) CN^–, OH^–

Question. The IUPAC name of the compound shown below is

(a) 2-bromo-6-chlorocyclohex-1-ene
(b) 6-bromo-2-chlorocyclohexene
(c) 3-bromo-1-chlorocyclohexene
(d) 1-bromo-3-chlorocyclohexene 

Question. If C₅H₁₂ undergoes reaction with chlorine in the presence of sunlight, only one product is formed, than reactant is
(a) 3, 3-dimethylpropane
(b) 2, 3-dimethylpropane
(c) 1, 3-dimethylpropane
(d) 2, 2,-dimethylpropane

Question. Aryl halides are extremely less reactive towards nucleophilic substitution than alkylhalides. Which of the following accounts for this ?
(i) Due to resonance in aryl halides.
(ii) In alkyl halides carbon atom in C–X bond is sp2 hybridised whereas in aryl halides carbon atom in C–X bond is sp³ hybridized.
(iii) Due to stability of phenyl cation.
(iv) Due to possible repulsion there are less chances of nucleophile to approach electron rich arenes.
(a) (i), (ii) and (iv)
(b) (i), (ii) and (iii)
(c) (i) and (iv)
(d) (ii), (iii) and (iv)

Question.

obtained by chlorination of n-butane, will be
(a) l-form
(b) d-form
(c) Meso form
(d) Racemic mixture

Question. The organic compound used as feedstock in the synthesis of chlorofluorocarbons is
(a) CH₂Cl₂
(b) CHCl₃
(c) CH₃Cl
(d) CCl₄

Question. Which will undergo S_N2 reaction fastest among the following halogen compounds?
(a) CH₃CH₂F
(b) CH₃CH₂Cl
(c) CH₃CH₂Br
(d) CH₃CH₂I

Question. The replacement of chlorine of chlorobenzene to give phenol requires drastic conditions, but the chlorine of 2, 4-dinitrochlorobenzene is readily replaced since,
(a) nitro groups make the aromatic ring electron rich at ortho/para positions
(b) nitro groups withdraw electrons from the meta position of the aromatic ring
(c) nitro groups donate electrons at meta position
(d) nitro groups withdraw electrons from ortho/para positions of the aromatic ring 

Question. The correct order of reactivity of the halides, ethyl chloride (I) iso-propyl chloride (II) and benzyl chloride (III) in S_N1 reaction is
(a) I > II > III
(b) III > II > I
(c) II > I > III
(d) I > III > II

Question. Exposure of CCl₄ causes
(a) Liver cancer in human
(b) Damage to nerve cells
(c) Coma, unconsciousness
(d) All of these

Question. Chloroform cannot be prepared from which of the following?
(a) CH₃OH
(b) C₂H₅OH
(c) CH₃CHO
(d) (CH₃)₂CO

Question. Hydrocarbon (CH₃)₃CH undergoes reaction with Br₂ and Cl₂ in the presence of sunlight, if the reaction with Cl is highly reactive and that with Br is highly selective so no.of possible products respectively is (are)
(a) 2, 2
(b) 2, 1
(c) 1, 2
(d) 1, 1 

Question. CCl₄ is well known fire extinguisher. However after using it to extinguish fire, the room should be well ventilated. This is because
(a) It is flammable at higher temperatures
(b) It is toxic
(c) It produces phosgene by reaction with water vapour at higher temperatures
(d) It is corrosive