Important questions of Haloalkanes and Haloarenes for CBSE board exam/NEET

                   Haloalkanes and Haloarenes

                                                                                    Flow-Chart

 

 

S.No.	Chapter Name	Topic-Concept Name	VSA/SA/Long answerquestion
1	Haloalkanes and Haloarenes	Classification	VSA-70 SA TYPE-I (2MARKS)-12 SA TYPE-II (3MARKS)-12
		Nomenclature
		Nature Of C-X Bond
		Methods Of Preparation Of Haloalkanes
		Preparation Of Haloarenes Haloarenes
		Physical Properties
		Chemical Reactions
		Polyhalogen Compounds

 
 

VERY SHORT ANSWER TYPE QUESTIONS (1 Mark)

S.No.	Topic-Concept Name	VSA (1 Marks)
1	Polyhalogen Compounds	1.      The Chemical name of DDT is – a) Dichlorodinitrotoloune b) Dichlorodimethyletoloune c) Dichlorodiphenyltrichloroethane d) Dichlorodiphenyltrichloromethane. Ans- c
2	Polyhalogen Compounds	2.     The Chemical formulae of phosgene is – a) COCl2 b) CaOCl2 c) CaCO3 d) COCl Ans- a
3	Polyhalogen Compounds	3.     The antiseptic action of CHI3 is due to – a) Iodoform itself b) Liberation of free iodine c) Partially due to iodine and partially due to CHI3 d) None of the above. Ans- b
4	Classification	4.     Which one of the following is a gem-dihalide – a) CH3CHBr2 b) CH2BrCH2Br c) CH3CHBrCH2Br d) CH3CHBrCH2CH2Br Ans- a
5	Chemical Reactions	5.  Which of the products will be major product in the reaction given below? Explain CH3CH=CH2 + HI →CH3CH2CH2I  + CH3CHICH3  (A)                      (B) a) Product (A)                      b) Product (B) c) Product (A) and (B) both equally  d) None of these. Ans- b
6	Chemical Reactions	6.     Which is the most reactive towards SN1 reaction – a) C6H5CH2Cl b) C6H5CH(C6H5)Br c) C6H5CH(CH3)Br d) C6H5C(CH3)(C6H5)Br Ans- d
7	Methods Of Preparation Of Haloalkanes	7.    The reaction  is known as – a) Finkelstins reaction b) Stephen’s reaction c) Kolbe’s reaction d) Wurtz reaction Ans-a
8	Methods Of Preparation Of Haloalkanes	8.     The best method of conversion of an alcohol into an alkali halide is by treating the alcohol with – a) PCl5 b) SOCl2 in presence of pyridine c) PCl3 d) Dry HCl in presence of anhyde.ZnCl2
9	Polyhalogen Compounds	9.     What is DDT among the following – a) A fertilizer b) Biodegradeable pollutant c) Non-Biodegradeable pollutant d) Green House Gas.
10	Methods Of Preparation Of Haloalkanes	10.  The catalyst used in the preparation of the alkyl chloride by the action of dry HCl on an alcohol is – a) Anhydrous AlCl3 b) FeCl3 c) Anhydrous ZnCl2 d) Cu
11	Nomenclature	11.  The IUPAC name of the compound shown below is – a) 2-Bromo-6-Cholorocyclohex-1-ene b) 6-Bromo-2-Cholorocyclohexene c) 3-Bromo-1-Cholorocyclohexene d) 1-Bromo-1-Cholorocyclohexene
12	Methods Of Preparation Of Haloalkanes	12.  The Addition of HBr to Pent-2-ene gives – a) 2-Bromopentane only. b) 2-Bromopentane only c) 2-Bromopentane and 3-Bromopentane d) 1-Bromopentane and 3-Bromopentane
13	Chemical Reactions	13.  Consider the following bromides – The correct form of SN1 reactivity is a) I>II>III b) II>III>I c) II>I>III   d) III>II>I
14	Preparation Of Haloarenes   Haloarenes	14.  The reaction of chlorine with toluene in presence of ferric chloride give predominantly- a) Benzyl chloride b) M-chlorotoluene c) Benzoyl chloride d) o-and p-chlorotoluene
15	Chemical Reactions	15.  Which of the following is not chiral – a) 1-Bromopentane . b) 2,3 –di-Bromopentane. c) 2-Hydroxy Propanoic acid d) 2-Butanol Ans- a
16	Chemical Reactions	16.  In the following reaction  the product  “X” is- a) C6H5CH2OCH2C6H5 b) C6H5CH3 c) C6H5CH2CH2C6H5 d) C6H5CH2OH
17	Chemical Reactions	17.  Consider following reaction   which of the following statement is true for ”X” a) It has nitrogen linked to ethyl carbon b) It gives propionic acid on hydrolysis c) It has an ester function d) It has cyanide group
18	Chemical Reactions	18.  Identify the set of reagent and reaction conditions “X” and ”Y” in the following set of transformations – a) X = dilute aqueous NaOH, 200 C Y = HBr/Acetic Acid, 200 C   b) X = Concentrated alcoholic NaOH, 800 C Y = HBr/Acetic Acid, 20 C   c) X = dilute aqueous NaOH, 200 C Y = Br2/CHCl3, 200 C d) X = Concentrated alcoholic NaOH, 800 C Y = Br2/CHCl3, 00 C
19	Chemical Reactions	19.  Following is the substitution reaction in which –CN replaces -Cl To obtain propane nitrate, R-Cl should be- a) Chloroethane b) Chloropropane c) Chloromethane d) 2- chloropropane
20	Chemical Reactions	20.  When 2-chloro-2-methylbutane is heated with alcoholic KOH, the possible products is/are i.) (CH3)2C=CHCH3 ii.) CH2=C(CH3)CH2CH3 iii) (CH3)2CHCH=CH2 a) (i),(ii) and (iii) b) (i) and (iii) c) (ii) and (iii) d) (i)and (ii)
21	Methods Of Preparation Of Haloalkanes	21.  The reaction conditions leading to the best yield of C2H5Cl are (incomplete) a)   b)  c)  d)
22	Chemical Reactions	22.  Which of the following is not chiral – a) 1-Bromopentane . b) 2,3–di-Bromopentane. c) 2-Hydroxy Propanoic acid d) 2-Butanol Ans- a
23	Chemical Reactions	23.  Aryl halides do not undergo nucleophilic substitution reactions under ordinary condition because - 1) Approach of nucleophile is retarted 2) Carbon carrying halogen atoms is sp3 hybridised 3) The substrate molecules is destabilized due to resonance 4) Partial double bond character between carbon and halogen a) 2 and 4 only b) 2 and 3 only c) 1 and 3 only d) 1 and 4 only
24	Physical Properties	24.  Iodine containing hormone in human body is ____________.
25	Nomenclature	25.  The name of tetrachloro derivative of methane is _________.
26	Physical Properties	26.  Dipole moment of 1,2- dichlorobenzene is lower than that of 1,4 –dichlorobenzene due to __________.
27	Nomenclature	27.  In allylic halide the halogen atoms is bonded to a __________ hybrid carbon atom.
28	Polyhalogen Compounds	28.  Chloroform is slowly oxidised by air in the presence of light to form extremely poisonous gas named as ______________
29	Chemical Reactions	29.  The freshly prepared diazonium salt is mixed with __________ to prepare chlorobenzene by   Sandmeyer’s reaction.
30	Methods Of Preparation Of Haloalkanes	30.  The addition of HBr in the presence of organic peroxide on But-1-ene follows__________ rule.
31	Nomenclature	31.  The IUPAC name of sec-Butyl chloride is ______________
32	Chemical Reactions	32.  The chemical composition of Lucas reagent is _____
33	Chemical Reactions	33.  Haloarenes require more drastic conditions than benzene towards _________ substitution reaction.
34	Chemical Reactions	34.  Out of 1-Bromobutane , 2-Bromobutane and 2-Bromo-2-methylpropane,___________ has highest boiling point.
35	Methods Of Preparation Of Haloalkanes	35.  Iodopropane can be prepared from chloropropane by refluxing it with ________________.
36	Chemical Reactions	36.  The major product in nitration of Chlorobenzene is __________
37	Methods Of Preparation Of Haloalkanes	37.  The synthesis of Fluoroethane with the help of bromoethane can be prepared by ________ reaction.
38	Chemical Reactions	38.  16. Chlorobenzene is ortho and para directing due to _________ effect.
39	Chemical Reactions	39.  The treatment of alcoholic KOH with chloroethane leads to the formation of_____________
40	Chemical Reactions	40.  When chloroethane is treated with AgCN,_______ is the major product.
41	Chemical Reactions	41.  In unimolecular nucleophilic substitution reaction of haloalkanes , the rate of reaction depends on _______
42	Preparation Of Haloarenes   Haloarenes	42.  Toluene undergoes electrophilic substitution with chlorine in the presence of sunlight to form____________
43	Chemical Reactions	43.  Out of 1-Bromobutane , 2-Bromobutane , 2-Bromo-2-methylpropane, _______will undergo SN1 as well as racemisation during hydrolysis with aqueous KOH.
44	Chemical Reactions	44.  When 2-Bromobutane is treated with alcoholic KOH, the major product is ____________
45	Chemical Reactions	45.  A mixture of 50% d-form and 50% of l-form of 2-Bromobutane is called _________.
46	Chemical Reactions	46.  Identify A and B in each of the following processes
47	Nomenclature	47.  Draw the structure of 4-bromo-3-methylpent-2-ene.
48	Polyhalogen Compounds	48.  Chloroform stored in closed dark coloured bottles completely filled so that air is kept out. Why?
49	Chemical Reactions	49.  An alkyl halide having molecular formula C4 H9 Cl is optically active. What is its structure?
50	Nomenclature	50.  Write IUPAC name of iodoform.
51	Nomenclature	51.   Write the IUPAC name of the following:
52	Chemical Reactions	52.  Which one of the following two substances undergo SN1 reaction faster and why? A). 1.     ch one of the following two substances undergo SN1 reaction faster and why?
53	Chemical Reactions	53.  Arrange the following in order of their increasing reactivity in nucleophilic substitution reactions - CH3F, CH3I, CH3Br, CH3Cl
54	Polyhalogen Compounds	54.  Why iodoform show antiseptic properties?
55	Chemical Reactions	55.  Optically active 2-iodo-2-methylbutane on treatment with NaI in acetone gives a product which does not show optical activity?
56	Chemical Reactions	56.  The presence of nitro group  at ortho or para positions increase the reactivity of haloarenes towards nucleophilic substitution reactions. Explain.
57	Chemical Reactions	57.  For the preparation of alkyl chlorides from alcohols, thionyl chloride (SOCl2 ) is preferred. Give reason.
58	Physical Properties	58.  The dipole moment of chlorobenzene is lower than that of cyclohexylchloride?
59	Chemical Reactions	59.  What are ambident nucleophiles? Give one example.
60	Methods Of Preparation Of Haloalkanes	60.  R-X can be prepared by free radical halogenations of alkenes.Why?
61	Physical Properties	61.  Boiling point of R-X is higher than hydrocarbon with similar molecular mass.Why?
62	Physical Properties	62.  Boiling point of R-I is higher than R-Cl with same alkyl group. Why?
63	Chemical Reactions	63.  SN1 is carried out in polar solvent. Why?
64	Chemical Reactions	64.  Allylic halides and benzaylic although 10 halide, but follow SN1 mechanism. Why?
65	Chemical Reactions	65.  Reactivity R-I is more than R-F towards SN reaction. Why?
66	Nomenclature	66.  Give the full name and structure of DDT.
67	Methods Of Preparation Of Haloalkanes	67.   What happens when bromine attacks CH2—CH—CH2—C≡CH?
68	Chemical Reactions	68.  Chlorobenzene is extremely less reactive towards a nucleophilic substitution reaction. Give two reasons for the same.  (iv) Due to repulsion between nucleophile and electron-rich arenes.
69	Chemical Reactions	69.  What happens when CH3—Br is treated with KCN?
70	Chemical Reactions	70.  What happens when ethyl chloride is treated with aqueous KOH?

 

 

SHORT ANSWER-I TYPE QUESTIONS (2 Marks)

 

S.No.	Topic-Concept Name	SA TYPE-I (2 Marks)
71	Nomenclature	1.      Write the IUPAC names of the following compounds : (i). (CH3 )3CCH2Br (ii).
72	Methods Of Preparation Of Haloalkanes Preparation Of Haloarenes Haloarenes	2.     Complete the following reactions-(incomplete) A).  B).
73	Methods Of Preparation Of Haloalkanes Preparation Of Haloarenes Haloarenes	3.     What happens when - (i) Propene is treated with HBr in presence of peroxide. (ii) Benzene is treated with methyl chloride in presence of AlCl3.
74	Chemical Reactions	4.      Explain as to why haloarenes are much less reactive than haloalkanes towards nucleophilic substitution reactions.
75	Chemical Reactions	5.     Which ones in the following pairs of substances undergoes SN2 substitution reaction faster and why?
76	Chemical Reactions	6.     Which compound in each of the following pairs will react faster in SN2 reaction with —OH? Why?  (i) CH3Br or CH3I (ii) (CH3)3 CCl or CH3Cl
77	Methods Of Preparation Of Haloalkanes	7.    What happens when bromine reacts with ? How would you justify this reaction?
78	Chemical Reactions	8.     Although chlorine is an electron withdrawing group, yet it is ortho-, para-directing in electrophilic aromatic substitution reactions. Explain why it is so?
79	Chemical Reactions	9.     What are ambident nucleophiles? Explain giving an example.
80	Chemical Reactions	10.  Explain as to why (i) Alkyl halides, though polar, are immiscible with water. (ii) Grignard’s reagents should be prepared under anhydrous conditions.
81	Physical Properties	11.  Explain why (i) the dipole moment of chlorobenzene is lower than that of  cyclohexyl chloride. (ii) haloalkanes are only slightly soluble in water but dissolve easily in organic solvents.
82	Chemical Reactions	12.  (a) Why does p-dichlorobenzene have a higher m.p. than its o- and m- isomers?  (b) Why is (±) – Butan-2-ol is optically inactive?

 

SHORT ANSWER-II TYPE QUESTIONS (3 Marks)

 

 

S.No.	Topic-Concept Name	SA TYPE-II (3 Marks)
83	Polyhalogen Compounds	1.     (i) State one use each of DDT and iodoform. (ii) Which compound in the following couples will react faster in SN2 displacement and why? (a) 1-Bromopentane or 2-bromopentane (b) 1-Bromo-2-methylbutane or 2-bromo-2-methylbutane.
84	Chemical Reactions	2.     How would you differentiate between SN1 and SN2 mechanisms of substitution reactions? Give one example of each.
85	Chemical Reactions	3.     Answer the following: A). Identify chiral in CH3CHOHCH2CH3 and CH3CHOHCH3. B). Among the following compounds, which one is more easily hydrolysed and why?       CH3CHCICH2CH3 or CH3CH2CH2CH2Cl C).Which of these will react faster in SN 2 displacement and why? 1-bromopentane or 2-bromopentane
86	Physical Properties	4.     Answer the following: (i) Haloalkanes easily dissolve in organic solvents, why? (ii) What is known as a racemic mixture? Give an example. (iii) Of the two bromo derivatives, C6H5CH(CH3)Br and C6H5CH(C6H5)Br, which one is more reactive in SN1 substitution reaction and why?
87	Chemical Reactions	5.     Rearrange the compounds of each of the following sets in order of reactivity towards SN2 displacement: (i) 2-Bromo-2-methylbutane, 1-Bromopentane, 2-Bromopentane (ii) 1-Bromo-3-methylbutane, 2-Bromo-2methylbutane, 3-Bromo-2-methylbutane (iii) 1-Bromobutane, 1-Bromo-2, 2-dimethylpropane, 1-Bromo-2-methylbutane
88	Chemical Reactions	6.     Answer the following questions: (i) What is meant by chirality of a compound? Give an example. (ii) Which one of the following compounds is more easily hydrolysed by KOH and why?       CH3CHClCH2CH3 or CH3CH2CH2Cl (iii) Which one undergoes SN2 substitution reaction faster and why?
89	Chemical Reactions	7.     Consider the three types of replacement of group X by group Y as shown here. This can result in giving compound (A) or (B) or both. What is  the process called if (i) (A) is the only compound obtained? (ii) (B) is the only compound obtained? (iii) (A) and (B) are formed in equal proportions?
90	Classification	8.     Write the structure of primary, secondary and tertiary – A. Alkyl halide. B.  Allyl halide
91	Nomenclature	9.     Write the IUPAC name to the following:         A) (CH3)3C-CH=C(Cl)C6H4I-p,                     B) CHF2CBrClF         C) ClCH2Cº CCH2Br
92	Nomenclature	10.  Write the structure of following comounds- A). Propylidene dichloride B). Iso-propylidiene dichloride C). Propylene dichloride
93	Classification	11.  Draw the structures of all the eight structural isomers that have the molecular formula C5H11Cl. Name each isomer according to IUPAC system and classify them as primary, secondary or tertiary chloride.
94	Classification	12.  Write the suitable example of each A.    Alkyl halide. B.    Allyl halide C.    Vinyl halide D.    Benzyalic halide E.    Aryl halide

 Ans coming soon.