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(Important Questions) Chemistry : Important Questions For CBSE Class XII ( Haloalkanes and Haloarenes)

Chemistry : Important Questions For CBSE Class XII ( Haloalkanes and Haloarenes)

(Q.1) Choose the incorrect statement about the benzyl chloride: ( 1 mark )
(a) It is less reactive than alkyl halides.
(b) It can be oxidized to benzaldehyde by boiling with copper nitrate solution.
(c) It is a lachrymatory liquid and answers beilstein’s test.
(d) It gives a white precipitate with alcoholic silver nitrate

(Q.2) Dry ether
The reaction RX + 2Na + RX _______________? R-R + 2NaXis called. ( 1 mark )
(a) Sandmeyer’ reaction
(b) Fittig reaction
(c) Wurtz reaction
(d) Williamson’s synthesis

(Q.3) Substitution of chlorine takes place readily at higher temperature in : ( 1 mark )
(a) CH3CH=CH2
(b) H2C=CH2
(c) HC C
(d) None of the above

(Q.4) (CH3)3CMgBr on reaction with D2O gives: ( 1 mark )
(a) (CH3)3CD
(b) (CH3)3COD
(c) (CD3)3CD
(d) (CD3)3OD

(Q.5) The silver salt of fatty acid on refluxing with an alkyl halide gives an: ( 1 mark )
(a) Acid
(b) Ester
(c) Ether
(d) Amine

(Q.6) Which of the following is the most reactive towards nucleophilic substitution reaction? ( 1 mark )
(a) C6H5Cl
(b) CH2=CHCl
(c) ClCH2CH=CH2
(d) CH3CH=CHCl

(Q.7) The molecule with the highest dipole moment is: ( 1 mark )
(a) CH3Cl
(b) CH2Cl2
(c) CHCl3
(d) CCl4

(Q.9) What is added to chloroform to prevent to form phosgene gas: ( 1 mark )
(a) CH3COCH3
(b) C2H5OH
(c) CH3COOH
(d) CH3OH

(Q.10) The most reactive nucleophile among the following is: ( 1 mark )
(a) CH3O-
(b) C6H5O-
(c) (CH3)2CHO-
(d) (CH3)3CO-

(Q.11) The correct order of decreasing dipole moment is: ( 1 mark )
(a) CH3Cl, CH3Br, CH3F
(b) CH3Cl, CH3F, CH3Br
(c) CH3Br, CH3Cl, CH3F
(d) CH3Br, CH3F, CH3Cl

(Q.12) HCl and HI do not give anti- markovnikov’s addition to alkenes in the presence of peroxides because: ( 1 mark )
(a) Both are highly ionic
(b) One is oxidizing and other is reducing
(c) One of the step is endothermic in both the cases
(d) All the steps are exothermic in both the reactions.

(Q.13) Which of the following is the correct: ( 1 mark )
(a) RF>RCl>RBr>RI
(b) RF>RBr>RCl>RI
(c) RCl>RBr>RF>RI
(d) RI>RBr>RCl>RF

(Q.14) HBr can be added easily to: ( 1 mark )
(a) CH2=CHCl
(b) CH3-CH=CH2
(c) ClCH=CHCl
(d) (CH3)2C=CH2

(Q.15) Which of the following is the most reactive towards the SN2 reaction: ( 1 mark )
(a) MeX
(b) RCH2X
(c) R2CHX
(d) R3CX

(Q.16) The correct order of Nucleophlicity is: ( 1 mark )
(a) CH3- < NH2- < HO- < F-
(b) NH2- > CH3- > HO- > F-
(c) CH3- > NH2- > HO- > F-
(d) NH2- > F- > HO- > CH3-

(Q.17) What are ambident nucleophiles? ( 1 mark )

(Q.18) 2-Phenyl-2-chloropropane on treatment with alc.KOH gives mainly: ( 1 mark )
(a) 2-Phenylpropene
(b) 3-Phenylpropene
(c) 1-Phenylpropan-2-ol
(d) 1-Phenylpropan-3-ol

(Q.19) When chlorine passed through propene at 400 degree Celsius, the product is: ( 1 mark )
(a) Vinyl chloride
(b) Allyl chloride
(c) PVC
(d) 1,2-dichloroethane

(Q.20) The IUPAC name of CH3-CH=CHCH2Br is: ( 1 mark )
(a) 1-Bromo-2-butene
(b) 1-Bromo-3-butene
(c) 2-Butene-1-bromide
(d) 4-Bromo-2-butene

(Q.21) Why is sulphuric acid not used during the reactions of alcohols with KI? ( 1 mark )

(Q.22) Write the IUPAC name of the following compound.
ClCH2CHClCH3 ( 1 mark )

(Q.23) Which is a better nucleophile, a bromide ion or iodide ion? ( 1 mark )

(Q.24) How will youget 1-bromopropane from propene? ( 1 mark )

(Q.25) Write the structure of 2-Chloro-3-methylpentane. ( 1 mark )

(Q.26) What is the nature of C-X bond of haloalkanes? ( 1 mark )

(Q.27) Arrange the compounds of each set in order of reactivity towards SN2 displacement:
2-Bromo-2-methylbutane, 1-Bromopentane, 2-Bromopentane. ( 1 mark )

(Q.28) What is an asymmetric carbon? ( 1 mark )

(Q.29) Which haloalkane has the maximum density and why? ( 1 mark )

(Q.30) What is Freon? ( 1 mark )

(Q.31) Write the full form of DDT. ( 1 mark )

(Q.32) Write a chemical reaction to illustrate Saytzeff’s rule. ( 1 mark )

(Q.33) Write the IUPAC name of the following structure. CH2BrCH=CHCH2CHCl2 ( 1 mark )

(Q.34) Arrange the following in increasing order of boiling point.
CH3CH2CH2CH2Br, (CH3)3CBr, (CH3)2CHCH2Br. ( 1 mark )

(Q.35) Explain why thionyl chloride reaction is preferred forpreparing alkyl chlorides from alcohols? ( 1 mark )

(Q.36) Arrange the following in order of their decreasing reactivity in nucleophile substitution reactions:
CH3F, CH3I, CH3Br, CH3Cl. ( 1 mark )

(Q.37) Define optical activity? ( 1 mark )

(Q.38) What are enantiomers? ( 1 mark )

(Q.39) What is racemic mixture or racemic modification? ( 1 mark )

(Q.40) Define retention? ( 1 mark )

(Q.41) The conversion of 2,3-dibromobutane to 2-butene with Zn and alcohol is a: ( 1 mark )
(a) Redox reaction
(b) Alpha-elimination
(c) Beta- elimination
(d) Both redox and Beta-elimination

(Q.42) Vicinal and gem dihalides can be distinguished by: ( 1 mark )
(a) aq. KOH
(b) Zn dust
(c) alc. KOH
(d) Br2

(Q.43) Which of the following have the highest boiling point: ( 1 mark )
(a) Chlorobenzene
(b) o-Dichlorobenzene
(c) m-Dichlorobenzene
(d) p-Dichlorobenzene

(Q.44) The most suitable reaction for the preparation of n-propylbenzene is: ( 1 mark )
(a) Friedel-crafts reaction
(b) Wurtz reaction
(c) Wurtz-fitting reaction
(d) Grignard reaction

(Q.45) Chlorobenzene can be obtained from benzene diazonium chloride by: ( 1 mark )
(a) Gattermann’s reaction
(b) friedel craft reaction
(c) Wurtz reaction
(d) Fittig reaction

(Q.46) Most reactive halide towards SN1 reaction is ( 1 mark )
(a) n-Butyl chloride
(b) sec-Butyl chloride
(c) tert-Butyl chloride
(d) Allyl chloride

(Q.47) When HBr is added to propene in the absence of peroxides, in the first step there is the addition of: ( 1 mark )
(a) H+
(b) Br –
(c) H
(d) Br

(Q.48) In the presence of benzoylperoxide propene reacts with HCl gas. The product is: ( 1 mark )
(a) 2-chloropropane
(b) Allyl chloride
(c) No reaction
(d) n-Propyl chloride

(Q.49) Cl2reacts with CS2in presence of I2to form ( 1 mark )
(a) CHCl3
(b) CCl4
(c) C2H5Cl
(d) Cl3C – NO2

(Q.50) If chloroform is left open in air in the presence of sunlight, it gives ( 1 mark )
(a) Carbon tetrachloride
(b) Carbonyl chloride
(c) Mustard gas
(d) Lewisite


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