1 . Carbanion is a :-
(A) Base (B) Nucleophile (C) Both (A) and (B) (D) None
2 . Electrophile is : (A) H
2O (B) NH
3 (C) AlCl
3 (D) C
2H
5NH
2
3 . Which of the following species has a pyramidal shape-
(A) CH3+ (B) BF3 (C) CH3– (D) C H3
4 . Increasing order (least basic first) of basic strength is shown by the set
(A) ClNH2, NH3, CH3NH2 (B) ClNH2, CH3NH2, NH3 (C) NH
3, ClNH
2, CH
3NH
2 (D) CH
3NH
2, ClNH
2, NH
3
5 . The decreasing order of acid strength indicated by the following sequence of reaction is :-
–C–H NaNH2 –C–Na C H2 2 HC CNa+ Ph CH3 H2O HC CH + NaOH
(A) NH3 > Ph3CH > C2H2 > H2O (B) H2O > HC CH > Ph3CH > NH3 (C) HC CH > H2O > Ph3CH > NH3 (D) Ph3CH > HC CH > H2O > NH3 6 . In which of the following compounds is hydroxylic proton the most acidic -
(A) O
F
H
(B) I O
H
(C)
O F H
(D)
O H F 7 . Correct arrangement of the following acids in correct Ka order is :-
(I) H3N—CH2—COOH (II) NC—CH2—COOH (III) H3C—CH2—COOH (IV) OOC —CH2—COOH (A) I > II > III > IV (B) II > I > III > IV (C) I > III > II > IV (D) IV > III > II > I 8 . Which of the following orders of acid strength is correct :-
(A) RCOOH > ROH > HOH > HC CH (B) RCOOH > HOH > ROH > HC CH (C) RCOOH > HOH > HC CH > ROH (D) RCOOH > HC CH > HOH > ROH 9 . Which of them is false for order of – I effect
(A) –F > –Cl > –Br > I (B) –NR > –NH > –NO3 3 2
(C) –OCH3 > –OH > –NH2 (D) > –C CH> H 1 0 . The order of basicity of halides is :
(A) Cl– < Br– < I– < F– (B) F– < I– < Br– < Cl– (C) I– < Br– < Cl– < F– (D) Cl– < F– < I– < Br–
EXERCISE-01 CHECK YOUR GRASP
SELECT THE CORRECT ALTERNATIVE (ONLY ONE CORRECT ANSWER)
1 1 . Which of the following molecule has longest C=C bond length -
(A) CH2=C=CH2 (B) CH3–CH=CH2
(C) CH –C–CH=CH3 2 CH3 CH3
(D) CH –C=CH3 2 CH3 1 2 . In the reaction CH3CN H O3
heat
CH3COOH
the hybridization state of the functional carbon changes from
(A) sp3 to sp2 (B) sp2 to sp3 (C) sp to sp2 (D) sp2 to sp 1 3 . Most stable carbocation is :-
(A) CH2
Cl
(B) CH2
NO2
(C) CH2
OCH3
(D) CH2
1 4 . Most stable carbanion is :-
(A) HC C (B) C6H5 (C) (CH3)3C—CH2 (D) (CH3)2C CH
1 5 . Consider the following carbocations
(a) CH O3 – –CH 2 (b) –CH 2 (c) CH3– –CH 2 (d) CH3—C H2
The relative stabilities of these carbocations are such that :-
(A) d < b < c < a (B) b < d < c < a (C) d < b < a < c (D) b < d < a < c 1 6 . Among the following, the strongest base is :-
(A) C
6H
5NH
2 (B) p–NO
2–C
6H
4NH
2 (C) m–NO
2–C
6H
4NH
2 (D) C
6H
5CH
2NH
2
1 7 . The increasing order of base strength of Cl–, CH3COO–, —OH and F— is :
(A) Cl– < F— < CH3COO– < —OH (B) Cl– > F— > CH3COO– > —OH (C) CH3COO– < Cl– < F— < —OH (D) None of these
1 8 . Formic acid is considered as a hybrid of the four structures
H–C O
–OH H–C O
= O H
H–C–O–H O
H–C–O–H O
I II III IV
Which of the following order is correct for the stability of the four contributing structures.
(A) I > II > III > IV (B) I > II > IV > III (C) I > III > II > IV (D) I > IV > III > II 1 9 . Which of the following carbonium ion is most stable
(A) Ph3C+ (B) (CH3)3 C+ (C) (CH3)2 CH+ (D) CH2 CH—CH2+
2 0 . Among the following the aromatic compound is (A)
(B)
(C) (D)
2 1 . Match List- I with List- II and select the correct answer using the codes given below -
Li st-I (Stabi li ty) Li st -II (Reason)
(A)
C H3C CH3
>
CH3+ (1) Inductive effect(B)
Br CH3
H C–C3
<
CH3– (2) Resonance(C) CH3
H C–C3 CH3
>
H3C–CH
2
+ (3) Hyperconjugation and resonance
(D)
CH• 2
>
CH• 2 H3C
CH3 (4) Hyperconjugation and inductive effect
Codes :
(A) A - 2 ; B - 3 ; C - 4 ; D - 1 (B) A - 3 ; B - 1 ; C - 4 ; D -2 (C) A - 4 ; B - 3 ; C - 1 ; D - 2 (D) A - 3 ; B - 4 ; C - 2 ; D - 1 2 2 . Which of the following compounds is the strongest base -
(A) NH2 (B) NH2 (C) CH3 NH2 (D) NHCOCH3 23. In which of the following molecule all the effect namely inductive, mesomeric & hyperconjugation operate:
(A) —Cl (B) —CH3
CH3
(C) —COCH3 CH3
(D)
2 4 . Which of the following reaction is possible :
(A) +
OH ONa
NO2
(B) CH –C–OH + HCOONa 3 O
(C) +
SO Na3 COOH
(D) H–CC–Na+H2O
2 5 .
COOH
X
, pKa value of the compound decreases if X is :-
(A) –NO2 (B) –NH2 (C) –OH (D) –OCH3
2 6 . Which one of the following results most stable carbon free radical : (A)
CH3
•
(B)
CH3
•
(C) (Ph)2C = C(Ph)2 CH3
•
(D) CH2 = CH2 CH3
•
2 7 .
CH – C CH3 – 2
H
1,2 shift
A (Major) ; Here A is :
(A)
CH – C – CH3 3
(B)
CH– CH2
CH3
(C)CH – C – H C–3 2
H
(D)
Ph CH – C = CH3 2
2 8 . –CH OH2 ; On dehydration with conc. H
2SO
4 forms predominantly :
(A) =CH2 (B) –CH3 (C) –CH3 (D) –CH3
2 9 . Which of the following is incorrect :
(A)
CH CH2 3 CHCH3
Cl•
•
+ HCl (B)
O
HO – C – H + C – H HO – C– H + H – C – H
H H H
:
O O O(C) CH – C 3 CH – C– CH3 2 H H–CH2
CH3
H shift
H
(D)CH CH CHO3 2 HO– CH C HCHO3 H O2
3 0 . The Ka values of alcohols, water and phenol are of order 10–17, 10–14 and 10–10 respectively. Which of the following reactions is possible :
(I) C6H5O + H2O C6H5OH + OH (II) C2H5O + H2O C6H5OH + OH
(A) Both I and II (B) only II (C) only I (D) neither of two
3 1 . Most stable carbanion is :
(A) CH3 (B) CH2 CH – CH2
(C) CH2
(D) CH2
NO2
3 2 . Stability of :
(I) C H3– C H = C H – C H3 (II) CH – C = C – CH3 3
CH3 CH3
(III) CH – C = CH3 2 CH3
(IV) CH – C = CH – CH3 3 CH3
in the increasing order is :
(A) I < III < IV < II (B) I < II < III < IV (C) I < IV < III < I (D) II < III < IV < I
3 3 . –MgBr + CH —CH2 2 H O2 [A]
O
; the product (A) is :
(A) –CH OH2 (B) –CH2CH2OH
(C) —CH—CH2 O
(D) No reaction
3 4 . Spin multiplicity of Triplet nitrene is :
(A) 1 (B) 2 (C) 3 (D) 4
3 5 . The maximum probability of proton loss is in the case of :
(A) CH – CH3 2
(B) CH C – CH3– 3 CH3
(C)
H H
(D) (CH ) C – CH3 2 2 H
3 6 . Select the least stable one :
(A) CH – CH3 2 (B) CH – CH – CH3 2 2 (C) CH– CH2
H C3
H C3 (D) C – CH2
H C3
H C3 H C3
3 7 . Which of the following will react fastest with conc. HCl :
(A) –CH2CH2OH (B) –CH(OH)CH3
(C) –OH (D) –CH2OH
3 8 . Consider the following reaction :
+ NaNH2 Product Br
OCH3
The product (P) and reaction (R) are :
(A)
OCH3
NH2
; addition-elimination (B)
OCH3
NH2
; elimination addition
(C)
OCH3 NH2
; elimination addition (D)
OCH3 NH2
; cine substitution
3 9 . Energy of activation is lower for which reaction : (A) RCH OH2 2 R C H2
(B) R CH OH2 2 R C H2
(C) R C OH3 2 R C3
(D) all have same Eact.
C HE C K Y OU R G R AS P
ANSWER KEY
E XE R CI S E - 1Q u e . 1 2 3 4 5 6 7 8 9 1 0 1 1 1 2 1 3 1 4 1 5
A n s . C C C A B D A B D C D C C A A
Q u e . 1 6 1 7 1 8 1 9 2 0 2 1 2 2 2 3 2 4 2 5 2 6 2 7 2 8 2 9 3 0
A n s . D A A A A B B C D A C A B C B
Q u e . 3 1 3 2 3 3 3 4 3 5 3 6 3 7 3 8 3 9
A n s . D A B C C D B C C
1 . The correct order of decreasing basic strength is :
N H
N H
N
NH2
I II III IV
(A) I > II > III > IV (B) II > III > I > IV (C) II > IV > I > III (D) II > III > IV > I 2 . The correct order of increasing dissociation constant of the following compound is :-
OH NO2
NO2
OH
NO2
OH NO2 NO2
NO2
OH
NO2
I II III IV
(A) II < IV < I < III (B) IV < III < I < II (C) IV < II < I < III (D) IV < I < II < III 3 . In the following arrange the H (numbered) for their ease of displacement during acid base reaction :
HO
OH
2 equivalent
H
(1) (3)
NaNH (liquid NH )2 3
(2)
(A) 1 > 2 > 3 (B) 3 > 2 > 1 (C) 3 > 1 > 2 (D) 2 > 3 > 1 4 . Which one of the following is the strongest base in aqueous medium :-
(A) (C2H5)3N (B) C2H5NH2 (C) NH3 (D) (C2H5)2NH
5 . The correct order of acid strength of the following compound is - (I) CH –C–CH3 3
O
(II) CH –C–3 C–CH3 O O
(III) CH –C–3 CH –C–2 CH3
O O
(A) III > II > I (B) III > I > II (C) II > I > III (D) I > II > III 6. Which of the following shows the correct order of decreasing basicity in aqueous medium -
(A) (CH3)3 N > (CH3)2NH > CH3NH2 > NH3 (B) (CH3)2 NH > (CH3)3N > CH3NH2 > NH3 (C) (CH3)2 NH > CH3NH2 > (CH3)3N > NH3 (D) (CH3)2 NH > CH3NH2 > NH3 > (CH3)3N 7 . For the compounds
N N N
O
H H
I II III
the order of basicity is -
(A) III > II > I (B) II > III > I (C) I > II > III (D) II > I > III
EXERCISE–02 BRAIN TEASERS
SELECT THE CORRECT ALTERNATIVES (ONE OR MORE THEN ONE CORRECT ANSWERS)
8 . Which of the following shows the correct order of decreasing acidity- (A) PhCO2H > PhSO3H > PhCH2OH > PhOH
(B) PhSO3H > PhOH > PhCO2H > PhCH2OH (C) PhCO2H > PhOH > PhCH2OH > PhSO3H (D) PhSO3H > PhCO2H > PhOH > PhCH2OH
79 . Give the correct order of increasing acidity of the following compounds-
OH OH COOH C CH
I II III IV
(A) II < I < III < IV (B) IV < II < I < III (C) I < II < IV < III (D) IV < I < II < III 1 0 . Which of the following is the most acidic
(A) CH2 = CH2 (B) HC CH
(C) CH2=CHCH2CH=CH2 (D)
1 1 . Which of the following substituents will increase the acidity of phenol -
(A) –NO2 (B) –CN (C) –CHO (D) – CH3
1 2 . (I) (II) (III)
Compare carbon-carbon bond rotation across I, II, III.
(A) I > II > III (B) I > III > II (C) II > I > III (D) II > III > I 1 3 . Which of the following s-bonds participate in hyperconjugation :
I V
H CH3 H
H II
III IV
(A) I and II (B) I and V (C) I and V (D) III and IV
1 4 . NH
(x)
, N–H
O (y)
, N
(z)
The correct order of decreasing basic strengths of x, y and z is :
(A) x > y > z (B) x > z > y (C) y > x > z (D) y > z > x
1 5 . Set the following in increasing order of their pKa values:
(x) CH —S—O—H3 O
O
(y) CH —C—O—H3 O
(z) CH —OH3
(A) y > x > z (B) x < y < z (C) y > z > x (D) x < z < y 1 6 . Rank the following alkenes in order of decreasing heats of hydrogenation (largest first):
(I) (II) (III) (IV)
(A) II > III > IV > I (B) II > IV > III > I (C) I > III > IV > II (D) I > IV > III > II 1 7 . Which of the following molecules has all the effects : inductive, mesomeric and Baker Nathan effect ?
(A) C2H5Cl (B) CH3–CH=CH2
(C) CH2=CH–CH=CH2 (D) CH3–CH=CH–C–
O CH3
1 8 . Which nitorgen in LSD (Lysergic acid diethylamide) is more basic :
H–N I
NII
–C–N(C H )2 5 2 OIII
CH3
(A) I (B) II (C) III (D) all are equally basic
1 9 . Which of the following substituted carboxylic acids has the highest Ka value :
(A) CH3—CH2—CH—
Cl
COOH (B) CH3—CH—
Cl
CH2—COOH
(C) CH —2 Cl
CH2—CH2—COOH (D) CH3—CH—
Br
CH2—COOH
SELECT THE CORRECT ALTERNATIVES (ONE OR MORE THEN ONE CORRECT ANSWERS) 2 0 . Which of the following compounds yield most stable carbanion after rupture of (C1–C2) bond :
(A) CH3—C—CCl3 O 1 2
(B) CH3—C—CBr3 O 1 2
(C) CH —CH3 2—C—CI3 O 1 2
(D) None of these
2 1 . N H pyrrole (I)
pyridine (II) N
aniline (III) NH2
Which is/are correct statements ?
(A) I is more basic than II (B) II is more basic than I and III (C) III is more basic than II (D) all are aromatic bases 2 2 . Following is true for stability between the two structures :
(A) CH –CH–CH=CH3 2 O
> CH –C=CH–CH3 3 O
(B) CH2=CH–CH=CH–CH2• > CH –C–CH–CH2 3
CH2
•
(C) CH =C–CH2 2
CH3
> CH3–CH=CH–C H2
(D) —O < CH –C–O
3
O
2 3 . Which have acidic hydrogen :
(A) CH3COOH (B) —OH (C)
O
CH —C3 —CH —CN2 (D) NaNH2 2 4 . C—C and C=C bond lengths are unequal in :
(A) Benzene (B) 1,3 buta-di-ene
(C) 1, 3 cyclohexa-di-ene (D) None
2 5 . The acid strength of substituted carboxylic acids is known to be dependent on the nature and position of the substituent. In the following examples, an attempt has been made to arrange the acids in order of acid strength, the strongest first. One of the series is incorrect-which one :
(A) CH3.CH2CH(Cl).COOH > CH3 .CH(Cl).CH2COOH > CH3.CH2.CH2.COOH (B) NO2.CH2.COOH > HOCH2. COOH > CH3.COOH
(C) Cl3C.COOH > BrCH2.COOH > FCH2.COOH (D) CH3.COOH > CH3.CH2.COOH > (CH3)3C.COOH 2 6 . Which species is not aromatic :
(A) N
(B) (C) NH (D)
N
:
2 7 . Select the correct option :
(A) carbonic acid is weaker acid than acetic acid
(B) the boiling points of acids are higher than corresponding alcohols (C) chloroacetic acid is stronger acid than acetic acid
(D) phenol is more acidic than ethanol 2 8 . Which reacts with AgNO3 to give ppt. :
(A) —Br (B) –CH=CH–CH Br2 (C)
—Br
(D) —Br
2 9 . Which statement is ture :
(A) NH– 2 is stronger base than OH– (B) NH2–OH is less basic than NH3
(C) CH3–NH2 is weaker base than N(CH3)3 in (aq) medium
(D) NH2
is weaker base than
CH –2 NH2
3 0 . Which is less acidic than phenol :
(A) OH
—CH 3
(B) CH3–OH (C)
OH
—NH 2
(D) H2O 3 1 . The precursor carbocation to the product in the following reaction is :
OH H
C H6 5 H
H
C H6 5
(A) C H6 5
(B) C H6 5 (C) either of the two (D) none of the two 3 2 . Which of the following ion is formed in the following reaction :
OH
H
O
(A)
OH
(B)
OH
(C) OH
CH2
(D) All of three
3 3 .
OD
D NaOH
CO2 [Intermediate] D P. Product is :
(A)
OD HOOC D
(B)
OD DOOC D
(C)
OH DOOC D
(D) Reaction not possible
3 4 . Predict the nature of A in the following reaction :
+ ClCH COOC H2 2 5 Base O
(A)
(A)
CH COOC H2 2 5 O
(B) CCOOC H2 5 Cl
(C) CHCOOC H2 5 O
(D) CHCOOC H2 5 O
3 5 . Which of the following intermediate is most likely to be formed during addition of HBr on crotonic acid : CH3CH = CHCOOH + HBr(g) CH3CH
Br
–CH2COOH :
(A)CH CH – C HCOOH3 2
(B) CH CH – CH COOH3 2
(C) CH CH=CH–C–OH3
OH
(D) none of these 3 6 . Which will give most stable cation upon strong heating :
(A)
CH – Cl2
(B) (Ph)3C–Cl (C)
Cl
(D) CH CH2 CH –Cl2
3 7 .
H
—Cl
Cl
(A); Here (A) is :
(A)
(B)
(C) (D)
3 8 . Cl – C – C – F F Cl F
–F [X] ; Here [X] is :
(A) Cl – C = C – F Cl F
(B) Cl – C = C – Cl F F
(C) Cl – C = C – F F Cl F
F
(D) C l – C = C – F
3 9 .
H C3 CH3
H H C C
H
CH3
H
H C3 CHCl3
KOH the reaction proceeds via :
(A) carbene (B) Carbon free radical (C) Carbocation (D) Carbanion
4 0 . :C
N H
• •
Cl
Cl (A) ; Here A is :
(A) N
(B) N H
Cl
(C) N Cl
(D) N
Cl
4 1 . Which of the following can give benzyne :
(A)
Cl H NaNH2
(B)
N2
(C)
Cl Br NaNH2
(D) All
4 2 . Dehydration of the following in increasing order is :
(I) –OH (II) –OH (III) –OH (IV) –OH
(A) I < II < III < IV (B) II < III < IV < I (C) I < III < IV < II (D) I < IV < II < III 4 3 . Increasing tendency for SN1 and SN2 reaction is :
(I) CH3CH2CH2CH2Cl (II) CH CH CH – CH3 2 3
Cl
(III)CH CHCH – Cl3 2 CH3
(IV) CH C – Cl3– CH3
CH3 (A) SN1 ; I < I I I < I I < I V (B) SN2 ; IV < II < II I < I
(C) (A) and (B) both are correct (D) Both incorrect 4 4 . Cyclopentyl ethyl ether can be obtained by :
(A) –ONa+CH CH Br3 2 (B) –Br+CH CH ONa3 2
(C) –OH+CH CH Cl3 2 (D) none is correct
4 5 . Major product in the following reaction is :
–Br + KOCH CH2 3 Product
(A) –OCH CH2 3 (B) (C) —Br
OCH CH2 3 (D)
4 6 . Mechanism of insertion reaction is of :
(A) One step for triplet carbene (B) Two step for singlet carbene (C) One step for singlet carbene (D) Two step for both
4 7 .
H C3
1 2 5 3 6
–Cl
NH2
(P)
4
. The most probable structure of intermediate P is :
(A)
OCH3
1 2 3 5 6
4
(B)
1 2 3 5 6
4
OCH3
(C)
OCH3
1 2 3 5 6
4
(D)
1 2 3 5 6
4
OCH3
4 8 .
CH3
1 2 5 3 6
–Cl
NH2
(A)
4
. The most probable structure of intermediate A is :
(A)
CH3
1 2 3 5 6
4
(B)
CH3
1 2 3 5 6
4
(C)
CH3
1 2 3 5 6
4
(D)
CH3
1 2 3 5 6
4
4 9 . Hybridisation of arrow headed 'C' is
(A) sp2 sp3 (B) sp3 sp3 (C) sp2 sp2 (D) sp3 sp3d
5 0 . Which of the following is most strongest electrophile : (A) singlet H – N• •
•• (B) triplet H – N• •
•• (C) singlet – C (D) triplet – C – 5 1 . In benzyne two external unshared electronic orbital :
(A) do not overlap to form a bond (B) can overlap to form a complete bond (C) poorly overlap to form a ver y weak bond (D) contribute in benzene ring
5 2 . Which of the following is aromatic intermediate :
(A) carbene (B)
•
(C) Benzyne (D) •
•
5 3 . In which of the following case 'H' shift is more preferable than 'CH3' shift :
(A)
CH3 CH – C – CH3 2
H
(B)
CH3
CH – C – 3 CH – C – H
H H
CH3
(C)
CH3
CH – C – 3 CH – CH3 Ph
(D) all
5 4 . Which of the following will not give 1, 2, shift :
(A)(CH ) C — C H3 3 2
(B) (CH ) C CH—CH3 3 2 Hg2
(C)
OH
(D) all
5 5 . Which of the following reactions is wrong : (A) CH CH CHO3 2 OH
CH – CH – CHO3
(B)
CH CH2 3 CHCH3 + HCl Cl
•
•
(C)
O
HO – C – H + H – C – H HO – C– H + H – C – H
H H
O O O
(D) CH – C 3 CH – CH – CH3 2 CH3
CH3
Hydride shifting
CH3
5 6 . Methyl benzylic carbonium ion is the most stable one, hence it will react fastest consider the following reaction :
CH3 H H
Br + OH SN2 (P) ; product (P) will be :
(A)
CH3 H HO
H
(B)
CH3 H HO
H
(C)
CH3
H OH H H
(D)
CH3 H OH
H H
5 7 . Consider the following reaction - R – CH = CH2+ IN3A , A is : (A) R – CH – CH N2 3
I
(B) R – CH – CH I2 N3
(C) R – CH – CH2 N
I
(D) R – CH – CH N
5 8 . + CHBr31 BuOK product ; product will be :
(A)
Br
Br (B)
Br Br Br
Br
(C)
Br
(D) Br
5 9 . HBr
CH2
major product will be :
(A)
Me
Br
(B)
CH Br2
(C)
CH Br2
(D)
CH3
Br
6 0 . O
O CH3
CH3
OH Product ; major product of the reaction can be :
(A)
O
(B)
O
(C)
O
(D)
O
6 1 . CH3COCH3 + BrCH2COOEt
2 ( i ) Zn ( ii ) H O / H
(A) ; the product (A) is :
(A) CH3 C
OCH3 Br CH3
(B)
OH CH3
CH –C–CH COOEt3 2
(C) CH3 C OH COOEt CH3
(D) CH3 C Br
OCH COOEt2 CH3
6 2 . Which carbocation is more likely to be formed in the dehydration of
OH
H :
(A)
(B)
(C)
(D)
6 3 . The most probable structure for (P) in the following reaction is :
2 conc H SO2 4 (P)
(A) (B) (C) (D)
6 4 . Which of the following alcohols is dehydrated most readily with conc. H2SO4 ?
(A)
CHOHCH3
(B)
CHOHCH3
OCH3
(C)
CHOHCH3
NO2
(D)
CHOHCH3
Cl 6 5 . Dehydration of alcohols by conc. H2SO4 takes palce according to following steps :
CH –C–CH OH3 2 CH –C–CH OH3 2 2
CH –C–CH3 3 CH =C–CH2 3
CH3 CH3
CH3 CH3
H H
H
• •
• • step -I
–H O2
step -II CH –C–CH3 2
CH3 H
1,2–H shift –H
step -III step -IV
the slowest and fastest steps in the above reaction are : (A) step I is slowest, while III is fastest
(B) step II is slowest, while III is fastest (C) step II is slowest, while IV is fastest (D) all step proceed at equal rate
6 6 . Pyrrole is treated with alkaline chloroform to form two products A and B ?
KOH
N N
H H
+ CHCl3
CHO +
Cl
(A) (B)
N
Which of the following intermediate is likely to be formed ?
(I) N
H
CCl 2 (II) N
H
(III) N• •
C Cl
Cl (IV)
N
(A) I and IV (B) I and III (C) III and IV (D) I, III and IV
6 7 . conc. H SO2 4
OH
Major product is :
(A) (B) (C) (D)
B RA I N T E A S E R S
ANSWER KEY
E XE R CI S E - 2Q u e . 1 2 3 4 5 6 7 8 9 1 0 1 1 1 2 1 3 1 4 1 5
A n s . D C B D A C D D B D A ,B,C C B B B
Q u e . 1 6 1 7 1 8 1 9 2 0 2 1 2 2 2 3 2 4 2 5 2 6 2 7 2 8 2 9 3 0
A n s . D D B A A B,D A ,C A ,B,C C C B A ,B,C ,D B,D A ,D A ,B,D
Q u e . 3 1 3 2 3 3 3 4 3 5 3 6 3 7 3 8 3 9 4 0 4 1 4 2 4 3 4 4 4 5
A n s . A B C D C C C A A D D A A A B
Q u e . 4 6 4 7 4 8 4 9 5 0 5 1 5 2 5 3 5 4 5 5 5 6 5 7 5 8 5 9 6 0
A n s . C A B C B C C A B D A B C A B
Q u e . 6 1 6 2 6 3 6 4 6 5 6 6 6 7
A n s . B C C B C B C
TRUE OR FAL SE :
1 . In benzene, carbon uses all the three p-orbitals for hybridization.
2 . All the carbon atoms in bicyclbutane are sp2-hybridized.
3 . Allene (CH2=C=CH2) is a planar molecule.
4 . The greater stability of trans-but-2-ene over cis-but-2-ene can be explained on the basis of hyperconjugation effect.
5 . In a two step reaction, the rate determining step has the lowest energy of activation.
FILL IN THE BLANKS :
1 . Out of benzene, ethylene and acetylene, the carbon-carbon bond is longest in ... . 2 . The cyclopentadienyl cation is ... while cyclopentadienyl anion is ... .
3 . The type of delocalization involving sigma bond orbitals with bond or vacant orbital is called ...
4 . Hydroperoxide ion is a stronger ... but weaker ... than hydroxide ion.
5 . Catalytic hydrogenation of cis-2, 3-diphenyl-2-butene gives... . MATCH THE COLUMN
1 . Match the column I with column II.
C o l u m n - I C o l u m n - I I
( A ) — N O2 ( p ) – m effect
( B ) — O– ( q ) + m effect
( C ) — O — C H3 ( r ) + I effect
( D ) —C N ( s ) – I effect
2 . Match the column I with column II.
C o l u m n - I C o l u m n - I I
( A ) ( p ) Aromatic
( B ) ( q ) Non-aromatic
( C ) + ( r ) Anti-aromatic
( D ) ( s ) Aliphatic
EXERCISE–03
MISCELLANEOUS TYPE QUESTIONS3 . Observe the following compound P and match the column I with column II.
HOOC HO
SO H3
C CH
C o l u m n - I C o l u m n - I I
( A ) Strongest acidic group in P ( p ) 1
( B ) Weakest acidic group in P ( q ) 2
( C ) Number of Intra molecular ( r ) 3
H-Bonding in P
( D ) Number of mole of hydrogen ( s ) 4
gas that is liberated on reaction of 'P' with excess of sodium metal if one mole of P is used
ASSERTION & RE ASON QUESTION :
These questions contains, Statement-I (assertion) and Statement-II (reason).
(A) Statement-I is True, Statement-II is True ; Statement-II is a correct explanation for Statement-I (B) Statement-I is True, Statement-II is True ; Statement-II is NOT a correct explanation for Statement-I (C) Statement-I is True, Statement-II is False.
(D) Statement-I is False, Statement-II is True.
1 . Statement-I : Greater the s-character of the hybrid orbital, the smaller is its size.
B e c a u s e
Statement-II : Bond formed by the overlap of sp3-sp3 hybrid orbital is the longest while the bond formed by the overlap of sp-sp hybrid orbital is shortest.
2 . Statement-I : Me C3
is more stable than Me C H2
and Me C H2
is more stable than the Me C H2
. B e c a u s e
Statement-II : Greater the number of hyperconjugative structures, more is the stability of carbocation.
3 . Statement-I : Cyclopentadienyl anion is much more stable than allyl anion.
B e c a u s e
Statement-II : Cyclopentadienyl anion is aromatic in nature.
4 . Statement-I : CH3OCH3 and C2H5OH have comparable molecular masses but boiling point of C2H5OH is higher than dimethyl ether.
B e c a u s e
Statement-II : C2H5OH forms intermolecular H-bonding while CH3OCH3 forms intramolecular H-bonding.
5 . Statement-I : In the compound,
IV III II I
3 2
C H — C H — C N , the most electroegative carbon is II.
B e c a u s e
Statement-II : Carbon atom II has more s-character.
6 . Statement-I : pka1 of fumaric acid is more than maleic acid.
B e c a u s e
Statement-II : Conjugate base of fumaric acid is stabilised by intramolecular H-bonding.
7 . Statement-I : Carbocation (II) is more stable than carbocation (I) CH2
CH3
(I)
CH2
CD3
(II) B e c a u s e
Statement-II : Carbocation (II) has more positive inductive effect of –CD3 group as compared to –CH3 group.
8 . Statement-I : Carbon-oxygen bonds are of equal length in acetate ion.
B e c a u s e
Statement-II : Bond length decreases with the multiplicity of bond between two atoms.
9 . Statement-I : The potential energy barrier for rotation about C=C bond in 2-butene is much higher than that in ethylene.
B e c a u s e
Statement-II : Hyperconjugat ion effect decreases the double bond character.
1 0 . Statement-I : Pyrrolidine (II) is more basic than pyrrole (I).
N H
• •
(I)
N H
• •
(II) B e c a u s e
Statement-II : Protonated pyrrole has re sonance stabilization of positive charge in aromatic ring.
COMPREHENSION BASED QUESTIONS : Comprehensi on # 1
The intramolecular delocalisation of and /non-bonding electrons without any change in the position of atoms is called resonance. Delocalisation may occur in conjugated system involving carbon atom and atom other than the carbon. Delocalisation makes system stable. More is the number of resonating structures, more is the stability of the system. A conjugated structure is least stable when a higher electronegative atom has positive charge and when identical charges are present on adjacent atoms.
1 . The decreasing order of stability of the following resonating structures :
CH =CH—Cl 2 • • CH —CH=Cl – 2 + CH —CH= Cl + 2 • •–
(I) (II) (III)
is -
(A) I > II > III (B) II > III > I (C) III > II > I (D) I > III > II 2 . If A is PhCH2
and B is CH2=CH—CH2
, the greater number of resonating structure is of -
(A) A (B) B (C) both A and B (D) None of these
3 . Which of the following pairs represent resonance ?
(A) CH2=CHOH ; CH3CHO (B)
–
C H2–CHO ; H2C=CH–OH
(C) CH —C—CH3 3 O
; CH —C—CH3 2 OH
(D) CH —C—CH3 3 OH
; CH —C—CH3 3 OH +
H 4 . Examine the structures I and II for nitromethane and choose the statement correctly :
CH —N3
— —
CH —N3—
• • • •–
O O
• •– • •–
O O
(I) (II)
+ +2
• •
(A) II is less important because electrons have shifted to oxygen (B) II is less important because nitrogen has sextet of electrons (C) II is acceptable and important structure
(D) none of these
5 . Examine the following two structures for pyrrole and choose the correct statement given below :
N• •
O
N• •
O (I) (II)
– +
(A) II is not an acceptable resonating structure because carbonium ions is less stable than nitride ion (B) II is not an acceptable resonating structure because there is charge separation
(C) II is not an acceptable resonating structure because nitrogen has ten valance electrons (D) II is an acceptable resonating structure
6 . Delocalization of electrons increases molecular stability because : (A) Potential energy of the molecule decreases
(B) Electron-nuclei attraction decreases (C) Both (A) and (B)
(D) Electron-electron repulsion increases Comprehensi on # 2
Carbocation is a group of atoms with positively charged carbon atom having six electrons in the valence shell after sharing. Carbocations are formed in the heterolysis of a bond and are planar species. Stability of carbocation is determined by inductive effect, hyperconjugation and resonance effect. Greater the number of contributing structures, more is the stability of a Carbocation. Electron releasing groups (+I effect) increases the stability of a carbocation whereas the electron withdrawing groups (–I effect) have an opposite effect.
1 . Which of the following is most stable carbocation ?
(A) C H3
(B) CH — C H — CH3 3
(C) CH — C H3 2
(D) CH —C—CH3 + 3 CH3
2 . The most stable carbocation among the following :
(A) (B)
(C) (D)
NO2
3 . In which of the following cases, the carbocation (I) is less stable than the carbocation (II) ?
(A) C6H5—C H2
(I), CH2= CH—C H2
(II) (B)
CH+ 2 (I),
CH+ 2 (II)
(C) CH2=C H
(I), CH3—C H2
(II) (D) H3C—C H2
(I), CH —2 CH2 F
(II)
4 . The most stable and the least stable carbocation among
(I), CH2=CH—C H2
(II), C6H5—C H2
(III)
and CH — C H — CH3 3
(IV) are respectively :
(A) II, I (B) III, IV (C) I, II (D) I, IV
5 . Most stable carbocation is formed by the heterolysis of :
(A) (CH3)3CBr (B) (C6H5)3CBr (C) (C6H5)2CHBr (D) C6H5CH2Br Comprehensi on # 3
The most important condition for resonance to occur is that the involved atoms in resonating structure must be coplanar or nearly coplanar for maximum delocalisation. If this condition does not fulfil, involved orbitals cannot be parallel to each other and as a consequence delocalisation cannot occcur. Bulky groups present on adjacent atoms inhibit the of orbitats. This phenomenon is known as steric inhibition of resonance.
Steric inhibition of resonance has profound effect on
(1) Physical properties (2) Acidity and basicity (3) Reactivity of organic compounds 1 . Arrange the following in the increasing order of basicity :
(I) NH2
(II)
NH2
(III)
NH2
NO2
(IV)
NH2
NO2 (A) I > II > III > IV (B) IV > III > II > I (C) II > I > IV > III (D) I > IV > III > II 2 . Which of the following is most acidic :
(A)
COOH
CH3
(B)
COOH
NO2
(C)
COOH
CH3
(D)
COOH
3 . Consider the following two structures and choose the correct statements - N
O
:
O+
(I)
N O O
:
+
(II)
(A) carbon-nitrogen bond length structure I is greater than that in structure II (B) carbon-nitrogen bond length in structure I is less than in structure II (C) carbon-nitorogen bond length in both structure is same
(D) It can not be compared
4 . Arrange the following carbocation in the increasing order of stability : CH2
CH3
(I)
CH2
(II) NO2
CH2
(III) NO2
CH–CH3 CH3
CH –CH3 CH3
(A) I < II < III (B) II < III < I (C) III < II < I (D) III < I < II Comprehensi on # 4
1-Butene (A) and 1,3-Butadiene (B) differ not only in the number of bonds, but (B) also has and bonds at alternate positions. This type of the system is called conjugate system. Following are some of the conjugate system.
CH =CH–C–H2 CH =CH–C–OH2
O O
acrolein acrylic acid benzene
in such systems, electron shifting takes place consecutively giving permanent polarity on the chain. This type of -electron shift in the conjugate systems is called mesomeric effect or resonance.
Rule s for re sona nce for ms :
(i) Individual resonance forms are imaginary, not real
(ii) Resonance forms differ only in the placement of their electrons or nonbonding electrons.
(iii) Different resonance forms of a substance don't have to be equivalent.
(iv) Resonance forms must be valid Lewis structures and obey normal rules of valencey.
(v) The resonace hybrid is more stable than any individual resonance.
Rules for stabi li ty :
(i) Structures with more covalent bonds are more stable than other structures.
(ii) Structures in which all of the atoms have a complete valence shell of electrons (i.e. the noble gas structure) are especially stable and make large contribution to the hybrid.
(iii) Stability is decreased by an increase in charge separation.
(iv) Str ucture that carr y negat ive charge on a more electronegat ive atom and positive charge on less electronegative atom are comparatively more stable.
1 . In which of the following compound, resonance is not possible :
(A) CH2 CH – N Me3
(B)
OH2
(C)
N
:
(D)O
2 . Which of the following statement is incorrect -
(A) In a resonance hybrid all the molecules are the same. A resonance hybrid cannot be expressed by any single structure.
(B) The value of the resonance energy of any resonance hybrid is not an absolute value (C) The energy of hybrid structures is always less than that of any resonating structure (D) Only one individual resonating structure explains all characteristics of the molecule 3 . Choose the correct option about stability of resonating structure :
(A)
Cl
: : :
>
Cl
(B) N O
<
O
N
(C) O
<
C O O
(D) H–C–O O
>
CH –C–O3
O
Tr u e / Fa l s e
1. F 2. F 3. T 4. F 5. F
F i l l i n t h e B l a n k s
1. benzene 2. antiaromatic, aromatic 3. hyperconjucation 4. nucleophile, base 5. 2,3-diphenylbutane (optically inactive, meso)
M a t c h t h e C o l u m n
1. (A) p,s ; B q,r ; (C) q,s ; (D) p,s 2. (A) q ; (B) p ; (C) p ; (D) r 3. (A) p ; (B) q ; (C) p ; (D) q
A s s e r t i o n - R e a s o n Q u e s t i o n s
1. B 2. A 3. A 4. C 5. A
6. C 7. D 8. B 9. D 10. C
C o mp re he n s i o n B a s e d Q u e s t i o n s
C o mp re he ns i o n # 1 : 1. (A) 2. (A) 3. (B) 4. (B) 5. (C) 6. (C) C o mp re he n s i o n # 2 : 1. (D) 2. (C) 3. (C) 4. (D) 5. (B)
C o mp re he ns i o n # 3 : 1. (C) 2. (B) 3. (B) 4. (B) C o mp re he ns i o n # 4 : 1. (A) 2. (D) 3. (C,D)
M IS C E L L AN E OU S T Y P E Q U E S T IO N
