Title HALOALKANES AND HALOARENES,,.pdf ✅

UNIT 3 HALOALKANES AND HALOARENES Exercise 1: NCERT Based Topic-wise MCQs 7.0 INTRODUCTION 1. Haloarenes contain halogen atom(s) attached to hybridised carbon atom. NCERT/Page-289 / N-159 (a) sp 3 (b) sp 2 (c) sp (d) both (a) and (b) 7.1 CLASSIFICATION 2. When two halogen atoms are attached to same carbon atom then it is: NCERT/Page-292 / N-162 (a) vic-dihalide (b) gem-dihalide (c) α, ω-halide (d) α, β-halide 3. Which of the following halide is 2 ∘ ? NCERT/Page-290 / N-160 (a) Isopropyl chloride (b) Isobutyl chloride (c) n-Propyl chloride (d) n-Butyl chloride 4. Which one of the following is not an allylic halide? NCERT Page N-160 (a) 4-Bromopent-2-ene (b) 3-Bromo-2-methylbut-1-ene (c) 1-Bromobut-2-ene (d) 4-Bromobut-1-ene 7.2 CLASSIFICATION 5. The IUPAC name of the compound shown below is NCERT Page-291 / N-161 (a) 2-bromo-6-chlorocyclohex-1-ene (b) 6-bromo-2-chlorocyclohexene (c) 3-bromo-1-chlorocyclohexene (d) 1-bromo-3-chlorocyclohexene 6. A compound is formed by substitution of two chlorine for two hydrogens in propane. The number of possible isomeric compounds is NCERT Page N-164 (a) 4 (b) 3 (c) 5 (d) 2 7. IUPAC name of (CH3 )3CCl is NCERT Page-291 / N-161 (a) 3-Chlorobutane (b) 2-Chloro-2-methylpropane (c) t-butyl chloride (d) n-butyl chloride 8. IUPAC name of CH3CH2C(Br) = CH − Cl is NCERT PAGE N- 162 (a) 2-bromo-1-chlorobutene (b) 1-chloro-2-bromobutene (c) 3-chloro-2-bromobutene (d) None of the above 9. Phosgene is a common name for NCERT PAGE N- 187 (a) phosphoryl chloride (b) thionyl chloride CONTACT 9163681973
(c) carbon dioxide and phosphine (d) carbonyl chloride 7.3 NATURE OF C-X BOND 10. The main difference in C − X bond of a haloalkane and a haloarene is NCERT Page-312/N-182 a) haloalkanes are less reactive than haloarenes due to difficulty is C − X cleavage in haloalkanes. b) in haloalkanes the C attached to halagen in C − X bond is sp 3 hybridised while in haloarenes it is sp 2 hybridised. c) C − X bond in haloalkanes is shorter than haloarenes. d) C − X bond in haloarenes acquires a double bond character due to higher electronegativity of X than haloalkanes. 11. C − Cl bond of chlorobenzene in comparison to C − Cl bond in methyl chloride is NCERT Page-312 / N-182 (a) Longer and weaker (b) Shorter and weaker (c) Shorter and stronger (d) Longer and stronger 7.4 METHODS OF PREPARATION OF HALOALKANES 12. Halogenation of alkanes is NCERT PAGE N- 164 (a) a reductive process (b) an oxidative process (c) an isothermal process (d) an endothermal process 13. Ethylene dichloride can be prepared by adding HCl to NCERT Page N − 165 (a) ethane (b) ethylene (c) acetylene (d) ethylene glycol 14. The best method for the conversion of an alcohol into an alkyl chloride is by treating the alcohol with (a) PCl5 NCERT Page-294 / N-164 (b) dry HCl in the presence of anhydrous ZnCl2 (c) SOCl2 in presence of pyridine (d) none of these 15. Conant-Finkelstein reaction for the preparation of alkyl iodide is based upon the fact that NCERT Page-295/N- 165 (a) sodium iodide is soluble in methanol, while sodium chloride is insoluble in methanol (b) sodium iodide is soluble in methanol, while NaCl and NaBr are insoluble in methanol (c) sodium iodide is insoluble in methanol, while NaCl and NaBr are soluble (d) the three halogens differ considerably in their electronegativity 16. Ethyl alcohol reacts with thionyl chloride in the presence of pyridine to give NCERT Page-294 / N-164 (a) CH3CH2Cl + H2O + SO2 (b) CH3CH2Cl + HCl (c) CH3CH2Cl + HCl + SO2 (d) CH3CH2Cl + SO2 + Cl2 17. 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 7.5 PREPARATION OF HALOARENES 18. In the preparation of chlorobenzene from aniline, the most suitable reagent is NCERT Page-296 / N-166 (a) chlorine in the presence of ultraviolet light (b) chlorine in the presence of AlCl3 (c) nitrous acid followed by heating with Cu2Cl2
(d) HCl and Cu2Cl2 19. Aryl halides can not be prepared by the reaction of aryl alcohols with PCl3, PCl5 or SOCl2 because (a) phenols are highly stable compounds. NCERT Page N-164 (b) carbon-oxygen bond in phenols has a partial double bond character. (c) carbon-oxygen bond is highly polar (d) all of these 20. Which of the following is the best method for synthesis of 1-bromo-3-chlorobenzene? (a) NCERT Page-296 / N-166 (b) (c) (d) 7.6 PHYSICAL PROPERTIES 21. The decreasing order of boiling points of alkyl halides is NCERT Page-298 / N-168 (a) RF > RCl > RBr > RI (b) RBr > RCl > RI > RF (c) RI > RBr > RCl > RF (d) RCl > RF > RI > RBr 22. Which of the following is liquid at room temperature (b.p. is shown against it)? NCERT Page N-168 (a) CH3I 42∘C (b) CH3Br 3 ∘C (c) C2H5Cl12∘C (d) CH3 F − 78∘C 23. Which of the following are gases at room temperature? NCERT Page N-168 (a) CH3Cl (b) C4H9Cl (c) C5H10Br (d) C3H7I 24. Which of the following isomer has the highest melting point: [CBSE Sample Paper 2021-22] (a) 1,2-dichlorobenzene NCERT Page-299 / N-168 (b) 1,3-dichlorobenzene (c) 1,4-dichlorobenzene (d) all isomers have same melting points 7.7 CHEMICAL REACTIONS 25. Which one is most reactive towards SN1 reaction? NCERT Page-304 / N-174 (a) C6H5CH(C6H5 )Br (b) C6H5CH(CH3 )Br (c) C6H5C(CH3 )(C6H5 )Br (d) C6H5CH2Br
26. A Grignard reagent may be made by reacting magnesium with NCERT Page-310 / N-180 (a) Methyl amine (b) Diethyl ether (c) Ethyl iodide (d) Ethyl alcohol 27. In SN1 reaction, the recemization takes place. It is due to NCERT Page-309 / N-179 (a) inversion of configuration (b) retention of configuration (c) conversion of configuration (d) Both (a) and (b) 28. The order of reactivities of the following alkyl halides for a SN2 reaction is NCERT Page-304 / N-174 (a) RF > RCl > RBr > RI (b) RF > RBr > RCl > RI (c) RCl > RBr > RF > RI (d) RI > RBr > RCl > RF 29. Which among MeX, RCH2X, R2CHX and R3CX is most reactive towards SN2 reaction? (a) MeX (b) RCH2X NCERT/ Page-304 / N-174 (c) R2CHX (d) R3CX 30. Isopropyl chloride undergoes hydrolysis by NCERT Page-304 / N-174 (a) SN1 mechanism (b) SN2 mechanism (c) SN1 and SN2 mechanisms (d) Neither SN1 nor SN2 mechanism 31. Tertiary alkyl halides are practically inert to substitution by SN2 mechanism because of (a) steric hindrance (b) inductive effect NCERT Page-302 / N-172 (c) instability (d) insolubility 32. Which of the following is an optically active compound? NCERT Page-307 / N-177 (a) 1-Butanol (b) 1-Propanol (c) 2-Chlorobutane (d) 4-Hydroxyheptane 33. The mechanism of SN1 reaction is given as: NCERT Page N-179 R − X ⟶ R ⊕ X ⊖ Ion pair ⟶ R ⊕ ∥ X ⊖ Solvent Separated ion pair ⟶ Y⊖ R − Y + X ⊖ A student writes general characteristics based on the given mechanism as : (1) The reaction is favoured by weak nucleophiles. (2) R ⊕. would be easily formed if the substituents are bulky. (3) The reaction is accompanied by racemization. (4) The reaction is favoured by non-polar solvents. Which observations are correct? (a) (1) and (2) (b) (1) and (3) (c) (1), (2) and (3) (d) (2) and (4) 34. The process of separation of a racemic modification into d-and l-enantiomers is called (a) Resolution (b) Dehydration (c) Revolution (d) Dehydrohalogenation 35. The major product in the reaction (a) t-Butyl ethyl ether (b) 2,2-Dimethyl butane (c) 2-Methyl pent-1-ene (d) 2-Methyl prop-1-ene 36. Racemic compound has NCERT Page-307 / N-177 (a) equimolar mixture of enantiomers (b) 1:1 mixture of enantiomer and diastereomer