DISTANCE LEARNING PROGRAM FOR IIT-JEE

45GOC - ISOMERISM

APEX INSTITUTE - 62, Nitikhand-III, Indirapuram, Ghaziabad Ph.No.-+91-9910817866, 0120-4901457,website : www.apexiit.co.in/

LEVEL - I

1. Propanone and propanal are :(a) geometrical isomers (b) chainisomers(c) functional isomers (d) position isomers.

2. Which of the following is not an isomer of 1-butyne ?(a) but-2-yne (b) buta-1, 3-diene(c) but-2-ene (d) methyl cyclopropene

3. Which of the following in not a cyclic isomer of C4H

7OH ?

(a) Cyclobutanol (b) cyclopropyl methanol(c) 1-methyl cyclopropanol (d) none of these

4. The total number of isomers of C4H

11N would be :

(a) 4 (b) 8 (c) 5 (d) 10

5. In which of the following molecules carbon does not involve sp3 hybridisation .(a) CH

2Cl

2(b) CH

2N

2(c) CH

2F

2(d) CF

2Cl

2

6. A compound with molecular formula C8H

14, contains 12 secondary and 2 tertiary H atoms .

The compound is :

(a) (b) (c) (d)

7. The total number of structural isomers possible for structure C3H

6 are :

(a) 1 (b) 2 (c) 3 (d) 4

8. How many geminal dihalides with different formula are possible for C3H

6Cl

2 ?

(a) only one (b) two (c) three (d) four

9. The compounds (CH3)

3N and CH

3CH

2CH

2NH

2 represent :

(a) chain isomerism (b) position isomerism(c) functional isomerism (d) all of the above

10. The number of isomeric aldehydes and ketones with formula C5H

10O are :

(a) 7 (b) 6 (c) 5 (d) 8

11. Nitroethane can exhibit one of the following kind of isomerism :(a) Metamerism (b) Optical activity (c) Tautomerism (d) Position isomerism

12. Which of the following is not an isomer of CH3CH

2CH

2CH

2OH ?

(a) CH3CH(CHO)CH

3(b) (CH

3CH

2)

2O

(c) CH3OCH

2CH

2CH

3(d) CH

3CH(OH)CH

2CH

3.

13. A . (D+ is catalyst) , compound A is :

(a) CH – C = CH – C – OC H3 2 5

OH O

(b) CH – C – CH = C – OC H3 2 5

OHO

(c) CH – C = CH – C – OC H3 2 5

OD O

(d) CH – C = CH – C – OC H3 2 5

OH O

GOC - ISOMERISM46


14. Tautomerism is not shown by :(a) CH

3COCH

2CN (b) HCN

(c) CH3CH=NOH (d) CH

3CN

15. How many isomers are possible for methyl anthracene ?(a) 2 (b) 3 (c) 4 (d) 5

16. Cyclohexane floats on water because :(a) it has low density (b) it has boat conformation(c) it has cyclic structure (d) it has planar structure

17. Which among the following compounds will show tautomerism ?(a) 2, 2-dimethyl propanal (b) 2, 2-dimethyl-1-nitropropane(c) Acetyl acetone (d) Benzophenone

18. Which of the following can show tautomerism ?

(a) (b) (c)

(d) all of these


(a) (b)

(c) (d)

20. Which of the following can show tautomerism ?(a) (CH

3)

3 CNO (b) (CH

3)

2NH (c) R

3CNO

2(d) RCH

2NO

2

21. Which will not show tautomerism ?

(a) (b) (c) (d)

22. Which will not show Tautomerism ?(a) CH

3CH

2CH

2CH

2NO

2(b) (CH

3)

2–CH–CH

2NO

2

(c) CH3

–CH2CH

3(d) (CH

3)

3C–NO

2

47GOC - ISOMERISM


23. Which will not show Tautomerism ?

(a) (b)

(c) (d)

24. Which of the following compound show tautomerism ?

(a) (H3C)

2CCl–CH=CH

2(b)

C=O

H(c) (H

3C)

2C(NO

2)–CH=CH–CHO (d) None of these

25. Which of the following is not an example of tautomeric equilibrium ?

(a)

(b)(c)

(d)

26. For which one of the following does the position of equilibrium lie to the left ?

(a)

(b)|OH

|OH

(c)

(d)

27. Which of the following will have highest percentage of enol content ?

(a) 52256 HOCCCHCHC||||OO

−−−− (b) 523 HCOCCH

||O

−−−

(c) 323 OCHCCHCCH

||||OO

−−−− (d) 323 CHCCHCCH||||OO

−−−−

28. Which among the following compounds will give maximum enol content in solution ?

(a) C6H5–C||O

–CH2––CH3 (b) CH3–C||O

–CH2––CH3

(c) CH2–C||O

–CH2–CH

2–CH

3(d) CH

3–C

||O

–CH2–COOC

2H

5

GOC - ISOMERISM48


29. The enol form of acetone, after treatment with D2O, gives :

(a) 23 CHC–CH

|OD

= (b) 33 CD–C–CD||

O

(c) DCH–CCH|

OH

22 = (d) 32 CD–CCD

|OD

=

30. Correct order of enolization is :(a) CH

3COCH

3 < CH

3COCH

2COOC

2H

5 < φCOCH

2COOC

2H

5 < CH

3COCH

2CHO

(b) CH3COCH

2COOC

2H

5 < φCOCH

2COOC

2H

5 < CH

3COCH

2CHO < CH

3COCH

3

(c) φCOCH2COOC

2H

5 < CH

3COCH

2CHO < CH

3COCH

3 < CH

3COCH

2COOC

2H

5

(d) CH3COCH

2CHO < CH

3COCH

3 < CH

3COCH

2COOC

2H

5 < φCOCH

2COOC

2H

5

31. I II III

Among the ketones which of the following is the correct order of the ease of their enolization .(a) I > II > III (b) III > II > I (c) II > I > III (d) III > I> II

32. I II III

Among these compounds which of following is the correct order of % enol content .(a) I > II > III (b) III > II > I (c) II > III > I (d) I > III > II

33. Compound H C–CH–CH –CH–OH3 2

O

is :

(a) tautomers of 3-oxobutanal and also show structural isomerism(b) tautomer of butanoic acid(c) compound does not show any isomerism(d) the compound can show structural isomers except tautomerism

34. Glucose is a hemiacetal and its structure is O

H

OH

OH

H

OH HOH

H

HH

CH OH2

.

Which of the following is correct ?(a) glucose show structural as well as stereo isomerism(b) diastereomer is convert to other diastereomer by ring chain tautomerism(c) both (a) and (b)(d) glucose conversion can not be predicted by its structure

35. Chloretone has a oscillating hydrogen due to(a) Keto-enol tautomerism (b) H-bonding(c) due to presence of chlorine (d) all of these

49GOC - ISOMERISM



(a) CH3

CH3

O

O (b)

(c) (d) All

37. Which of the following compound have higher enol content ?

I

C||O

CH3

OH

II

C||O

CH3

OH

(a) II (b) I (c) I = II (d) none of these

38. Which of the following compound have higher enol content ?

I

NO2

O

II

OCH3

O

(a) I (b) II (c) I = II (d) none of these

39. Which of the following compound have less enol content ?

I ON

|H

II N|

H

O

(a) I (b) II (c) both (a) & (b) (d) none of these

40. Highest percentage of enol form is possible in :

(a) (b)

(c) (d)

GOC - ISOMERISM50


41. All of the compounds shown are present together in various amounts at equilibrium. The mostabundant isomer is the one in which the least stabilized carbonyl group is enolized. Show that youunderstand the fundamental principles of enolization as well as the meaning of the precedingsentence by picking the species present in greatest amount at equilibrium.

(a) (b) (c) (d)

42. The addition NOCl on alkene the carbon can bear ‘NO’ group only if:-(a) that carbon can contain hydrogen(b) that carbon can not contain hydrogen(c) depends upon the hydrogen(d) the stability depends upon the no of C carbon atoms.

43. The compound C||O

N

H

can show :

(a) Amido-Imidol tautomerism (b) Nitro acinitro tautomerism(c) a prototopic tautomerism (d) Ring chain tautomerism

44. Phthalonyl chloride is also represented by the structure

C

C

ClCl

O

O

. This is an example of :

(a) Dehydrated form of Phthalonyl chloride (b) Tautomerism.(c) It is not a form of Phthalonyl chloride (d) Metamerism

45. Conversion of O....O

..

.. O....O..+

–

.. is :

A B(a) Example of valance tautomerism(b) The compound B is more stable than A(c) Compound ‘A’ is colourless and compound ‘B’ is red coloured compound.(d) All of these are right.

51GOC - ISOMERISM


46. This compound is an example of :

HO C H— —

H C OH— —

HO C H— —

H C OH— —

H C—

H C H— —

OH

O

O C

H

H C OH— —

HO C H— —

H C OH— —

H C— —OH

H C H— —

OH

H C—OH—

H C OH— —

HO C H— —

H C OH— —

H C—

H C H— —

OH

O

(I) (II) (III)(a) (I) and (III) are epimers (b) (I) (II) ring chain tautomerism(c) (I) and (III) are anomers (d) All of these

47. The erythrose is a example of :

H—C C C OH— — —C—

OHO H H

HOHH

H

H

OH

H H

OH

OH

H

(a) resonance (b) ring chain tautomerism(c) anionotropy (d) None of these

48. % enol content of acetyl acetone in H2O is 15% and is hexane is 92% because:

(a) more intramolecular hydrogen bonding in water(b) more intramolecular hydrogen bonding in hexane(c) less intermolecular hydrogen bonding in water(d) more intermolecular hydrogen bonding in hexane

49. The percentage of enolic form is:

I C|O

C||O

C

H

MeMe

H

II C|O

C||O

C

H

MeMe

Me

(a) equal (b) I > II (c) II > I (d) can not be predicted

GOC - ISOMERISM52


50.

OO

OOH

enol form is more stable due to :

I II(a) decrease the dipole dipole repulsion(b) double bond in Ring is more stable(c) hydrogen bonding is possible in enol form (d) none of these

51.O Na⊕

+ O Na⊕

NaOH

H O2

O

H /H O⊕2

OH +

OH

(Minor) (Major) (Major) (Minor)Reason of this conversions :(a) In acid catalysed enolization, more stable alkene is formed(b) In base catalysed enolization, less stable alkene is formed due to the resonance with

primary carbanion(c) Both (a) and (b)(d) Reason is not appropriate

52. Phenolphthalein is a example of

I

O

C||O

C

OH OH

II

OH

C||O

C

OH O

(a) tautomerism (b) resonance (c) acid-base reaction (d) none of these

53.

O

ON

HIsatin

Lactam

O

OHN

HLactim

are :

(a) Tautomerism(b) This tautomerism is also known as amido imidol tautomerism(c) Both (a) and (b) (d) None of these

54. The highest boiling point is expected for :(a) iso octane (b) n-octane (c) n-butane (d) 2,2,3,3-tetramethylbutane

55. Which pair of isomerism is not possible together ?(a) Chain and position (b) Functional and position(c) Tautomerism and functional (d) All of these

53GOC - ISOMERISM


56. An isomers of ethanol is :(a) methanol (b) acetone (c) diethyl ether (d) dimethyl ether

57. Which of the following statement is not true ?(a) Homologues cannot be isomers but isomers can be homologues(b) Isomers can not be homologous(c) The number of paired and unpaired electrons in various resonating forms is equal

58. Aldehyde show with each other :(a) Chain isomers (b) Position isomers(c) Functional isomers (d) Both (a) and (b)

59. Compound C4H10O can show :(a) Metamerism (b) Functional isomers(c) Functional isomers (d) All above

60. Acetamide is isomer of :(a) 1-amino ethanol (b) Formamide(c) Ethyl amine (d) Acetaldehyde oxime

61. How many isomers of C5H11OH will be primary alcohols :(a) 2 (b) 3 (c) 4 (d) 5

62. Which of the following is an example of position isomerism ?(a) Isopentane and neopentane (b) Glucose and fructose(c) Ethanol and dimethyl ether (d) α-Naphthol and β-naphthol

63. O-Cresol and benzyl alcohol are :(a) Functional (b) Position (c) chain (d) All

64. CH3CONH2 & HCONHCH3 are called :(a) Position (b) Chain (c) Tautomers (d) Functional

65. Choose the homologues

(a)

CH3

& (b)

OH

&

CH2OH

(c) CH3NH2 & (CH3)2NH (d) All the above

GOC - ISOMERISM54


LEVEL - II A

1. The stability of compounds is :

(i) (ii) (iii) (iv)

(a) (iv) > (iii) > (i) > (ii) (b) (i) > (iii) > (ii) > (iv)(c) (ii) > (iii) > (i) > (iv) (d) (iv) > (i) > (iii) > (ii)

2. Stability order of carbocation :

(I) C (II) (III)

C H73

C H73C H73

(IV) H2C=CH–CH2

(a) I > III > II > IV (b) II > III > I > IV(c) III > II > I > IV (d) III > I > II > IV

3. Stability of carbocation :

I F3C – CH2 II F

3C – CH

2 – CH2 III F C3

(a) III > II > I (b) I > II > III (c) II > I > III (d) III > I > II

4. The most stable radical :

(a) C6H

5• (b) H C – C – O3

O•

(c) H C3 C

H C3

H C3

• (d) C6H

5–C

CH3

CH3

5. Arrange the following alkenes in decreasing order of reactivity towards electrophilic additionClCH

2CH = CH

2(HC

3)

2C = CH

2H

3C – CH = CH

2 H

2C = CH – Cl

(i) (ii) (iii) (iv)(a) (i) > (iii) > (ii) > (iv) (b) (iv) > (iii) > (ii) > (i)(c) (ii) > (iii) > (i) > (iv) (d) (ii) > (iii) > (iv) > (i)

6. Consider the following three halides :(1) CH

3 – CH

2 – Cl (2) CH

2 = CH – Cl (3) C

6H

5 – Cl

Arrange C—Cl bond length of these compounds in decreasing order :(a) 1 > 2 > 3 (b) 1 > 3 > 2 (c) 3 > 2 > 1 (d) 2 > 3 > 1

7. C , C double bond length is minimum in :

(a) CH3 – CH = CH

2(b) CH

2Cl – CH = CH

2

(c) CCl3 – CH = CH

2(d) CCl

3 – CH = CH – CCl

3

8. Which one of the nitrogen containg compounds is an electropile ?(a) NH

2 – NH

2(b) NH

2 – OH (c) NF

3(d) NH

3

55GOC - ISOMERISM


9. Which among the following compounds behave both as an electrophile as well nucleophile .

CH2 = CH

2CH

3 –

O

C – CH3

CH2 = CH – CH2 CH

3 –

O

C– Cl 1 2 3 4(a) only 1 (b) 1 and 2 (c) 3 and 4 (d) 1

, 2

, 3 and 4

10. Ethyl alcohol is miscible with water in all proportions because :(a) of its acidic nature (b) it is neutral(c) it reacts with water (d) it forms H-bonds.

11. The pKa of acetylsalicylic acid (aspirin) is 3.5. The pH of gastric juice in human stomach is about2 − 3 and pH in the small intestine is about 8. Aspirin will be :(a) unionised in the small intestine and in the stomach(b) completely ionised in the stomach and almost unionised in the small intestine(c) ionised in the stomach and almost unionised in the small intestine(d) ionised in the small intestine and almost unionised in the stomach .

12. What is true about the following equilibrium ?

|ΘK⊕

H + H3C–C

|| CH |H

H+ H C–C3

|| C KΘ ⊕|(a) It will be almost completely shifted to the left(b) It will be almost completely shifted to the right(c) The equilibrium constant is very close to one(d) The equilibrium constant is zero

13. Use resonance arguments to rank the following in order of increasing acidity .

(a) Hc < Ha < Hb (b) Ha < Hb < Hc (c) Hb < Hc < Ha (d) Hc < Hb < Ha

14. The acidity of the protons H is :

(i) (ii) (iii)

(a) i > ii > iii (b) ii > i > iii (c) ii > iii > i (d) iii > i > ii

15. Which one of the hydrocarbon is the most acidic ?

|

|

|

| ||

||

CH3CH3

CH3CH3H

H C3

H C3

H C3

|

|

|

| ||

||

CH3

CH3

CH3

H

H C3

H C3

H C3H C3

(a) (b) (c) (d)

GOC - ISOMERISM56


16. 1,3-cyclopentadiene has a pKa = 15 whereas simple cycloalkanes have pKa > 50 with respectto their conjugate bases . This is because :(a) 1, 3-cyclopentadiene is aromatic. (b) 1, 3-cyclopentadiene is anti-aromatic.(c) 1, 3-cyclopentadine is non-aromatic.(d) 1, 3-cyclopentadiene is non-aromatic with an aromatic conjugate base.

17. The Ka values of alcohols, water and phenol are of order 10–17, 10–14 and 10–10 respectively .Which of the following reaction is possible ?(a) C6H5O

– + H2O → C6H5OH + OH– (b) C2H5O– + H2O → C2H5OH + OH–

(c) both (a) and (b) (d) neither of the two.

18. The pKa of the conjugate acids of :

(i) (ii) N..|

H

(iii)

(a) i > ii > iii (b) i > iii > ii (c) ii > i > iii (d) ii > iii > i

19. Which of the following represents the increasing order of pKa values of the C − H acids .

HCCCH3 −≡− OEtCCHCCH||||

OO

23 −−−− COOEtCH3 3CHPh −

(i) (ii) (iii) (iv)(a) ii < iii < i < iv (b) ii < i < iv < iii (c) iv < ii < iii < i (d) iii < ii < iv < i

20. What is the correct order of acidity of the following compounds .

(1) CH3CO2H (2) CHBr2 CO2H (3) HCOCHCH|Cl

23 −

(4) Me2CH−CO2H (5)

3

2

RN|

HCOCHMe

+

−−

(a) 2 > 5 > 3 > 1 > 4 (b) 5 > 3 > 2 > 1 > 4(c) 1 > 2 > 5 > 4 > 3 (d) 2 > 5 > 1 > 3 > 4

21. Among the following compounds ,

I II Et3N III IV

the order of basicity is :(a) IV > III > II > I (b) II > I > III > IV(c) III > IV > II > I (d) I > II > III > IV

22. Which is maximum basic in nature ?

(a) (b) (c) (d)

57GOC - ISOMERISM


23. The correct order of basicities of the following compounds is :

I II CH3 − CH2 − NH2 III (CH3)2 NH IV

(a) II > I > III > IV (b) I > III > II > IV(c) III > I > II > IV (d) I > II > III > IV

24. Which of the following is most acidic compound ?(a) CH3COOH (b) Cl CH2COOH (c) CH3OCH2COOH (d) HOCH2 COOH

25. Which among the following has strongest acidic character ?(a) Cyclohexanol (b) 3-nitrocyclohexanol(c) 4-methylcyclohexanol (d) 4-ethylcyclohexanol

26. Which one of the following is most acidic ?(a) Phenol (b) 2-chlorophenol (c) 3-chlorophenol (d) 4-chlorophenol

27. Most acidic compound of the following is :

(a) (b) (c) (d)

28. Which of the following is least basic ?(a) methyl lithium (b) dimethyl zinc(c) methyl magnesium chloride (d) methyl sodium

29. Rank of the following three compounds in decreasing order of basicity .

I II III

(a) III > I > II (b) III > II > I (c) II > I > III (d) II > III > I

30. Least basic character is shown by which compound amongst the following is :

(a) (b) (c) (d) all are equally basic

31. Which of the following carbocations is expected to be most stable ?

(a)

CH3

X H

(b)

CH3

X H

(c)

CH3

X

H(d)

CH3

X

H

GOC - ISOMERISM58


32. Which of the following species is/are aromatic ?

(a) (b) 6SbCl

(c)

Ph

Ph

(d)

H

33. Which of the following has the most acidic hydrogen ?(a) 3-hexanone (b) 2, 4-hexanedione(c) 2, 5-hexanedione (d) 2, 3-hexanedione.

34. Of the following order of reactivity of Cl with AgNO3 , which one is correct ?

(a) CH2 = CH –CH

2Cl > CH

3CH

2CH

2Cl > CH

3CH = CHCl

(b) CH2 = CH – CH

2Cl > CH

3CH

2CH

2Cl < CH

3CH = CHCl

(c) CH2 = CHCH

2Cl < CH

3CH

2CH

2Cl > CH

3CH = CHCl

(d) CH2 = CHCH

2Cl < CH

3CH

2CH

2Cl < CH

3CH = CHCl.

35. What is the decreasing order of stability of the ions ?

I II III

(a) I > II > III (b) II > III > I (c) III > I > II (d) II > I > III

36. Which of the following orders is not correct regarding the –I effect of the substituents ?

(a) – I < –

Cl < –

Br < –

F (b)

(c) (d)

37. Which compound has maximum solubility in water ?

(a) C6H

6(b) CH

2=CH

2(c) CH

3– –CH

3(d) CH

3CH

2CHO

38. Hydrogen bonding between NH3 and H

2O is shown as :

(a) (b)

(c) (d)

39. Which of the following statements is true about this molecule ?

(a) C5-N bond is longer than C1-N and C3-N bonds.(b) C5-N bond is shorter than C1-N bond and latter is shorter than C3-N bond.(c) All three C-N bonds are of same length.(d) C1-N and C3-N bonds are of same length but they are longer than C5-N bond.

59GOC - ISOMERISM


40. Which of the following statements is true about this molecule .

(a) C1-C2 and C3-C4 bonds are of same length.(b) C1-C2 bond is shorter than C3-C4 bond.(c) C1-C2 bond is longer than C3-C4 bond.(d) C1-C2 and C2-C3 bonds are of same length.

41. H–O–C≡N H–N=C=O(Cyanic acid) (Isocyanic acid)Loss of proton from these two acids produces :(a) same anion (b) different anions (c) same cation (d) different cations

42. A highly important canonical structure of this molecule is :

(a) (b) (c) (d)

43. I II III

Resonance energies of the cations are in the order :(a) II > I > III (b) I > II > III (c) III > II > I (d) III > I > II

44. I II III

Resonance energies of these compounds are in the order as :(a) I > II > III (b) III > II > I (c) II > I > III (d) III > I > II

45. I CH2=CH–OH II CH –CH=OH2

⊕

On moving from gas phase to water as solvent, the contribution of II in resonance hybrid(a) increases (b) decreases (c) remains constant (d) question is not correct

46. I II III

The order of the ease of ionization of these compounds to produce carbocations and is :(a) I > II > III (b) II > I > III (c) I > III > II (d) III > II > I

GOC - ISOMERISM60


47. Identify the major contribution in following resonance structures:

(a) NH2– −

⊕C

NH2|

NH2

& NH2– =C

NH2|

(b) CH3– C

O||

– – C

O||

–CH3

& CH3– C

O||

–CH= –CH3

(c) &

(d) CH3– –OH & CH

3– = –H

48. Which of the following statements is NOT true ?(a) Resonance forms must obey normal valency rules(b) Resonance forms are in equilibrium(c) The hybrid is more stable than the individual resonance forms(d) Resonance forms differ only in the distribution of electrons

49. I 22 CHCHCHCHCHCH =−=−= II 22 HCCHCHHCCHCH

Θ⊕

−=−−=

III 22 HCCHCHCHCHHCΘ⊕

−=−=−

Among these three canonical structures (through more are possible) what would be their relativecontribution in the hybrid :(a) I > II > III (b) III > II > I (c) I > III > II (d) III > I > II

50. Consider the three compounds below(i) CH3CH2OCH2CH3 (ii) CH3CH2CH2CH2CH3 (iii) CH3CH2CH2CH2OHThe two most similar in boiling point are ________ and the two most similar in solubility inwater are ________ .(a) i and iii , ii and ii (b) i and ii , i and iii(c) ii and iii , i and ii (d) i and iii , i and iii

51. Match the boiling points with the following three isomers of C4H10O2.CH3OCH2CH2OCH3 CH3CH2OCH2CH2OH HOCH2CH2CH2CH2OH

(a) 85ºC 230ºC 135ºC(b) 230ºC 85ºC 135ºC(c) 85ºC 135ºC 230ºC(d) 135ºC 230ºC 85ºC

52. Which substance would be expected to exhibit the greatest surface tension at 25°C .(a) CH

3 – O – CH

3(b) C

2H

5 – OH

(c) CH3 – CH – (OH) – CH

3(d) HO – CH

2 – CH

2 – OH

61GOC - ISOMERISM


53. Which of the following should have the lowest boiling point ?

(a) ||

|HO

Cl (b) ||

OH

Cl

(c) (d)

54. Which of the following are more viscous ?

(a) (b) (c) (d)

55. The hydrocarbons having high vapour pressure is :(a) 2 – methyl hexane (b) heptane(c) 3, 3 – dimethyl pentane (d) 2,2,3,3 – tetramethyl butane

56. If the dipole moment of toluene and nitro benzene are 0.43 D and 3.93 D, then what is theexpected dipole moment of p-nitro toluene ?(a) 3.50 D (b) 2.18 D (c) 4.36 D (d) 5.30 D

57. The compound having lowest dipolemoment is :

(a) CH2 = CH − Cl (b) CH ≡ C − Cl (c) CH3 − CH2 − Cl (d)

58. Which one of the following compounds will have the highest dipolemoment .

(a) | NO2

(b) (c) (d)

59. Which of the following options are correct for dipolemoment of the following compounds ?

(A)

NO2

(B)

NO2

CH3H3C

(a) µA > µ

B(b) µ

A = µ

B(c) µ

A < µ

B(d) 2 µ

A = µ

B

60. The dipole moment of

Cl

is 1.5 D . The dipole moment of

Cl

ClCl

Cl

is :

(a) 0 D (b) 1.5 D (c) 2.86 D (d) 2.25 D

GOC - ISOMERISM62


LEVEL -

II B

1. Which will not give AgCl on reaction with AgNO3 .

(a) H2C = CH – CH

2Cl

(b)

CH2–Cl

(c)

Cl

(d) CH3

CH3

Cl2. Arrange pH of the given compounds in decreasing order :

(1) Phenol (2) Ethyl alcohol (3) Formic acid (4) Benzoic acid(a) 1 > 2 > 3 > 4 (b) 2 > 1 > 4 > 3 (c) 3 > 2. > 4 > 1 (d) 4 > 3. > 1 > 2

3. Consider the given compounds(1) CH

3 – CH

2 – NH

2(2) CH

3 – CH = NH

(3) CH3 – C ≡ N (4) C

2H

5 – NH – C

2H

5

Arrange basicity of these compounds in decreasing order :(a) 4 > 1 > 2 > 3 (b) 1 > 2 > 3 > 4 (c) 1 > 4 > 2 > 3 (d) 4 > 1 > 3 > 2

4. Which of the following halides undergo solvolysis most easily ?(a) C

6H

5CH

2Cl (b) CH

2 = CH – CH

2Cl

(c) CH2 = CH – CHCl – CH

3(d) (C

6H

5)

3CCl

5. Which nitrogen in LSD is most basic ?

H—N(2)

N

CH3

C—N(C H )2 5 2

O(3)

(1)

(a) 1 (b) 2 (c) 3 (d) All are equally basic

6. Which is is the most basic among following pairs of compounds ?

(A) (I) (C2H

5)

3N & (II) N

(B) (I) CH3CH

2NHCH

2CH

3& (II)

N

H

(C) H2N—

O

C—NH2

& NH —C—NH2 2

NH

(a) A -

I

, B

-

II

, C

-

I (b) A

-

I

, B

-

I

, C

-

I

(c) A -

II

, B

-

I

, C

-

II (d) A

-

II

, B

-

II

, C

-

II

63GOC - ISOMERISM


7. Among

I H3CO COOH II Cl COOH

III O2N COOH(III) IV COOH

NO2

The correct order of increasing acid strength is :(a) I < III < II < IV (b) I < II < III < IV(c) II < I < III < IV (d) II < III < I < IV

8. Match the pKa with the appropriate phenol .

(a) 10.8 10.3 10.2 10.0 9.4(b) 10.3 8.0 9.4 10.2 10.0(c) 10.0 9.4 10.3 8.0 10.2(d) 9.4 10.2 8.0 10.0 10.3

9. Which vertical column correctly matches the pKa values ?pKa

1.0 43 10.0 15.8 4.2

43 1.0 4.2 4.2 15.8

10.0 4.2 15.8 43 10.0

15.8 10.0 43 1.0 1.0

4.2 15.8 1.0 10.0 43

(a) (b) (c) (d) (e)

10. Identify the most acidic structure –

(a) (b) (c) (d)

GOC - ISOMERISM64


11. Which balanced equation best describes the hydrolysis of the compound shown ? The reactionis carried out at a pH of 2 .

(a)

(b) | CNHCH + H O3 3+ | CNH + CH OH3 3

||O

||O

+

(c)

(d)

12. Which one of the following contains most acidic hydrogen atom ?

(a) (b) (c) (d)

13. The decreasing order of basicity of the following ethers towards 3BF is :

(i) ( ) OHC252 (ii) ( ) OCH

23 (iii)

23

3

CH|

OCHCH

−− (iv)

(a) iv > ii > i > iii (b) i > ii > iii > iv (c) iii > i > ii > iv (d) iv > ii > iii > i

14. Match the pKa with the appropriate ammonium ion .

|

|

+NH3

CN

(a) 4.0 4.6 2.4 5.1 5.4(b) 4.6 4.0 5.1 2.4 5.4(c) 5.4 2.4 4.0 4.6 5.1(d) 2.4 5.1 4.6 5.4 4.0

65GOC - ISOMERISM


15. The conjugated acid of , CH3− CH2−CH2−NH−CH2−CH2−NH NH2 is :

(a) CH3− CH2−CH2−NH−CH2−CH2−NH NH2

(b) CH3− CH2−CH2−NH−CH2−CH2− NH2

(c) CH3− CH2−CH2−NH−CH2−CH2−NH

(d) CH3− CH2−CH2− −CH2−CH2−NH NH2

16. Which of the following compound would be the most acidic ?

(a)

CHH

(b) CHH

(c) C

HH

(d)

17. For which one of the following does the position of equilibrium lie to the right ?

(a) + NH3

| CO¯||O

+ NH4+

(b) + NH3 + NH4+

(c) + NH3 + NH4+

(d) + NH3 + NH4+

18. Which of the following is the strongest acid ?

(a) (b) | CH CH NH2 32

+

|

+

(c) (d)

GOC - ISOMERISM66


19. Conjugate acid of –CH is :

(a) N–C. .

H–N⊕

H

||

H(b) NH2–CH ||:N

+

(c) N–C:N. .

H H2

⊕ (d) none of these

20. ANaNHmoles2 2 → . The product (A) will be :

(a) (b)

(c) (d)

21. From the following reactions : HC ≡ CH + LiNH2 NH3 + HC ≡ CLi and

H2O + HC ≡ CLi H — C ≡ C — H + LiOH.

Predict which of the following facts regarding the basic strength is correct.(a) Li NH2 > HC ≡ C Li > LiOH (b) Li NH2 > LiOH > HC ≡ CLi(c) HC ≡ C Li > LiNH2 > LiOH (d) HC ≡ C Li > LiOH > LiNH2

22. Which one of the following is the weakest base ?(a) 2-methyl-3-nitroaniline (b) 2-methyl-5-nitroaniline(c) p-nitroaniline (d) 3, 4-dinitroaniline

67GOC - ISOMERISM


23. Which one of the amines is the least basic ?

(a) (b)

(c) (d)

24. Which of the following is strongest base ?

(a) (b) (c) (d)

25. Strongest base among the following is :

(a) (b) (c) (CH3)3N: (d)

26. Which is the most basic among following pairs of compounds:

(A) I (C2H5)3 N & II (B) I CH3 CH2 NH CH2 CH3 & II

(C) I & II

(a) (A) - I , (B) - II , (C) - I (b) (A) - I , (B) - I , (C) - I(c) (A) - II , (B) - I , (C) - II (d) (A) - II , (B) - II , (C) - II

27. Which is more basic ?

(a)

H

N

..

(b) H

. .

N (c)

H

N

..

(d) H

N

..

28. The most acidic ‘H ’

(W) HO OH(Z)

CH OH(X)2

H

OHOO

(Y)Vitamin-C

is :

(a) X (b) Y (c) Z (d) W

29. I CH2=CH–OH II

On moving from gas phase to water as solvent, the contribution of II in resonance hybrid(a) increases (b) decreases (c) remains constant (d) question is not correct

GOC - ISOMERISM68


30. (CH3)

3COH is less acidic than (H

3C)

3SiOH because :

(a) Carbon is more electronegative than Si(b) (CH

3)

3SiOΘ is stabilized due to back bonding

(c) Bigger size of silicon than carbon (d) None of these

31. The most reactive positions for electrophilic substitution reaction of anthracene are

2

3

1

410

9

65

78

(a) 1 & 4 (b) 1 & 2 (c) 2 & 3 (d) 9 & 10.

32. I II III

The order of the C − N bond lengths among these compounds is :

(a) III > I > II (b) II > I > III (c) III > II > I (d) I > II > III

33. Among the following compounds which has longest C – O bond :

(a) (b) (c) (d)

34. The order of the ring − N bond lengths among these compounds is :

I II III

(a) III > I > II (b) III > II > I (c) I > II > III (d) II > III > I

35. I II III

The stability order of these canonical structures is :(a) I > II > III (b) II > III > I (c) I > III > II (d) III > I > II

36. I II III IV

Among these compounds the order of the π-electrons energies is :(a) IV > II > III > I (b) III > IV > II > I(c) III > I > IV > II (d) I > II > IV > III

37. I II III

Which of the following choice is the correct order of resonance energy of these molecules ?(a) I > II > III (b) II > I > III (c) III > I > II (d) III > II > I

69GOC - ISOMERISM


38. I II III

Which of the following choice is the correct order of resonance energy of these molecules ?(a) I > II > III (b) III > II > I (c) II > I > III (d) III > I > II

39. I

O•

II CH2=CH–

•CH

2 III CH

2=CH–

•CH–CH=CH

2

Which of the following choice is the correct order of resonance energy of these radicals ?(a) I > II > III (b) I > III > II (c) III > I > II (d) III > II > I

40. Which of the following has highest Kb value ?

(a) Ph–NH2, (b) (c) (d)

41. Ease of ionization to produce carbocation and will be maximum in which of the followingcompounds :

(a) (b) (c) (d)


(a) (b) (c) (d)


(a) (b) Br

(c) (d) Br

44. I II

III IV

Rotation about indicated bonds is easiest in which of these molecules :(a) I (b) II (c) III (d) IV

GOC - ISOMERISM70


45. Which is the most stable resonance form ?

(a) (b)

(c) (d)

46. Which is the most aromatic in character ?

(a)

N

H

N

H

(b)

S

(c)

O

(d)

N

47.CH CH2 2 HC CH

III

III IV

Rotation about indicated bonds is easiest in which of these molecules(a) I (b) II (c) III (d) IV

48.Cl

(a) Cl (b) Cl⊕ (c) Cl* (d) none

49. Which of the following compounds will be aromatic on treatment will LiAlH4 :

(a) (b) (c) (d)

50. An improvement in basic strength due to hydrogen bonding is observed in :

(a)

NH2 NH2

(b) NH2 (c)

22 NH–C–NH||O

(d) None of these

71GOC - ISOMERISM


LEVEL -

III

1. Fill in the blanks :(i) The positively charged carbon of carbonium ion contains ________ valence electrons .

(ii) NO2+ is/an ________ reagent .

(iii) The negatively charged carbon of carbanion is ________ hybridized .

(iv) Acetic acid is ________ acid than formic acid due to ________ effect of methyl group.

(v) Free radical is paramagnetic while carbonium and carbanion ion is ________

(v) Amongst CH CHO2

– , CH3

– and CH2

–—NO

2, the most stable carbanion is ________

(vi) The boiling point of dioxane is ________ than thioxane

.

(vii) They type of delocalization involving sigma bond orbitals is called ________

(viii) Hydroperoxide ion a stronger ________ but weaker ________ than hydroxide ion.

(ix) A reaction which occurs through a single transition state is called a ________ reaction.

(x) Free radicals are ________ but carbanions are ________

(xi) Amongst isomeric butenes ________ is the most stable.

(xii) In ethyl acetoacetate, it is the ________ form which is more stable while in acetylacetone, it is the________ form which is more stable.

(xiii) In propionic acid , the central carbon atom is _______ while in α-bromopropionic acid it is _______.

(xiv) An organic compound with the formula CH3CH

2CH

2OH shows functional, isomerism with

compound of the structural formula ________

(xv) Alkenes can exhibit position, chain and ________ isomerism.

(xvi) Ketones must contains at least ________ carbon atoms in order to exhibit metamerism .

(xvii) The number of isomers of molecular formula C8H

10 containing benzene ring are ________

(xviii) The possible number of dichloro derivatives of propane are ________

(xix) Ethyl benzene is ________ isomer to xylenes.

2. True and false(i) sp hybrid orbital is more electronegative than sp2 hybrid orbital.

(ii) The size of sp3 hybrid orbital of carbon is smaller than that of sp hybrid orbital.

(iii) The resonating structure differ in the number of unpaired electrons.

(iv) The resonance energy is defined as the difference between the enthalpy of formation of themolecule and that of resonating structure having the largest energy.

(v) Benzene has about 78 per cent contribution from Kekule’s structures.

(vi) Metamerism is due to the different arrangement of groups attached to a functional group.

(vii) Tautomers of a compound are in equilibrium with each other.

(viii) Chain isomers are possible for alkanes having four or more carbon atoms.

(ix) Maleic acid has zero dipole moment.

GOC - ISOMERISM72


(x) Of ethane, ethene and ethyne, the ethynic hydrogens are most acidic.

(xi) Propandiene has both sp and sp2 hybrid carbon atoms.

(xii) Methyl group belongs to –I group.

(xiii) The − OCH3 group belongs to + I group.

(xiv) Resonance and tautomerism refer to one and the same phenomenon.

(xv) The − OH and − NH2 groups attached to aromatic ring have only resonance effects.

(xvi) BF3 acts as a Lewis base.

(xvii) Stronger acids have lesser values of pKa as compared to weaker acids.

(xviii) In an equilibrium reaction CH3COOH CH3COO¯ + H+, CH3COOH and CH3COO¯constitute conjugate pair of acid and base.

(xix) In a carboxylic acid RCOOH, the factor stabilising the carboxylate anion, RCOO¯, relative toRCOOH increases the acidity of the acid.

(xx) + I group attached to carboxylic group weakens the acidity of carboxylic acid.

(xxi) The resonate stabilisation of formate anion makes formic acid stronger acid than acetic acid.

(xxii) Nucleophilic substitution reactoin involving SN1 mechanism is always associated with the inver-sion of configuration of carbon atom

(xxiii) The addition across C = O group is an electrophilic addition reaction.

(xxiv) Aryl halides are less reactive than alkyl halides towards nucleophilic reagents.

(xxv) In acylium ion, the structure R—C ≡ O: is more stable than R—C = O,

(xxvi) The stability of carbonium ions is influenced by both resonance and inductive effect. –I effectreduces the stability while +

I effect increases the stability fo carbonium ion.

(xxvii) m-chlorobromobenzene is an isomer of m-bromochlorobenzene.

(xxviii) Dichlorocarbene (:CCl2) is a nucleophile.

(xxix) Free radicals are produced by homolytic cleavage of covalent bonds.

(xxx) All electrophiles are positively charged.

(xxxi) Amongst CH3O¯ , HO¯ and CH3COO¯ ions nucleophilicity parallels basicity.

(xxxii) Simple carbanions are isoelectronic and isostructural with ammonia.

3. Choose the correct answer :(a) If both A and R are TRUE, and is the CORRECT explanation of A.(b) If both A and R are TRUE, but R is not the CORRECT explanation of A.(c) If A is TRUE but R is FALSE(d) If both A and R are FALSE.

Assertion (A) Reason (R)

(i) Tertiary carbonium ion are generally Hyperconjugative as well as inductive effect dueformed more easily than primary to additional alkyl groups stabilize tertiarycarbonium ions. carbonium ions

(ii) Singlet carbene has a linear structure. The carbon atom in singlet carbene is sp2-hybridized.

(iii) Carbanions like ammonia have pyramidal The carbon atom carrying negative charge hasshape. an octet of electrons.

73GOC - ISOMERISM


Assertion (A) Reason (R)

(iv) The carbocation CF3–CH2 is less In case of CF3–CH2, the strongly electron

stable than CF3. withdrawing –CF3 group intensifies the +ve charge

but in case of CF3, the lone pair of electrons oneach of the three F-atoms overlap with the emptyp-orbital of the carbocation carbon therebydispersing the +ve charge.

(v) Methylene has sextet of electrons around Methylene behave as a nucleophile.carbon but bears no formal charge.

(vi) N3¯ is a weaker base than NH2¯. The lone pair of electrons in on N atom in N3¯ is ain a sp2-orbital while in NH2¯ it is in an sp3-orbital.

(vii) Allyl free radicals is more stable than a The allyl free radical is stabilized by resonance.simple alkyl free radical.

(viii) Enol form of cyclohexane-1,3,5-trione is It contains α-hydrogen atomsmore stable than its keto-form.

(ix) Metamers can also be chain or position The term tautomerism was introduced to explainisomers the reactivity of a substance according to two

possible structures.

(x) All the carbon atoms in but-2-ene lie in All the carbon atoms of but-2-ene are sp2-one plane hybridized

(xi) All the hydrogen atoms in CH2=C=CH2 lie All the carbon atoms in it are sp2-hybridisedin one plane

(xii) C2H5O2N shows functional isomerims Nitroethane shows tautomerism due to presenceas well as tautomerism. of α-hydrogens and functional isomerism with

ethyl nitrite.

(xiii) Both ethyl acetoacetate and acetylacetone Keto group is a much better electron withdrawingexhibit keto-enol tautomerism but the group than an ester group.amount of enolic form is much higher inacetylacetone than in acetoacetic ester.

(xiv) Ethyl acetoacetate gives reddish violet It exists predominantly in the keto-formcolour on treatment with ferric chloride.

(xv) Benzaldehyde forms two oximes on The two oximes arise due to geometricalreacting with NH2OH. isomerism.

(xvi) Cyclobutane is less stable than Presence of ‘bent bonds’ causes loss of orbitalcyclopentane. overlap.

4. Pick out the correct match(i) Aseptic distillation (A) separation of keto and enol tautomers(ii) acetaldehyde (B) high percentage of enol(iii) Yeast (C) conversion of D-glucose to L-glucose(iv) Dipole moment measurement (D) distinguishing optical isomers

GOC - ISOMERISM74


LEVEL -

IV

SUBJECTIVE

1. Arrange the following according to their stability and give reason of your answer .

HC)CH(,HC,ClC,C)CH(,HCHC 233333256

2. Explain why boiling point of acetone is more than that of propanaldehyde although both havesame molecular weight ?

3. CH3Cl and CH

3OH both are polar compounds but CH

3OH is soluble in water where as

CH3Cl is not. Why ?

4. Explain why bp of RX is in the following order :R—I > R—Br > R—Cl > R—F

although dipole-dipole attraction is maximum in R—F and minimum in R—I:

5. Alkane has a molecular weight of 72 and monochlorination prduces one product only . What isthe compound.

6. Write down the structure of close homologous of heptane having in their molecular one ofquaternary carbon atom and the other having two tertiary carbon atom.

7. When propane reacts with Cl2, the reaction yield two compounds of the molecular formula

C3H

7Cl, One compound has a b.p. of 46.6ºC and the other b.p. of 36.5ºC. When the compound

with boiling point 46.6ºC is allowed to react with Cl2, the reaction gives three isomeric compounds

of molecular formula C3H

6Cl

2. When the compound with b.p. 36.5º reacts with Cl

2, only two

isomers of formula C3H

6Cl

2 are formed. Give the structure of all products.

8. Why allylic free radical CH2 = CH – 2C H

•

is more stable than CH3– CH

2 – 2C H

•

, while both

are primary free radicals .

9.

OH3

H

H1

OO

H4

H2

Arrange all these numbered H in order of their decreasing acidic strength.

10. Arrange the following compounds in order of increasing basicity.

(a) 3Cl C , 3 3, CH — O — CHCH3 N

CH3

CH3 (b) –

4 2 3N H , N H , NH+

11. Which of the following C—I bond is weak and why?

(a) 3 2CH O — CH — I (b) CH3 N

CH3

CH2 I

75GOC - ISOMERISM


12. Account for the following .

(a) –3CCl is less basic than –

3CF . (b) –I is weaker base than –F .

13. Explain the following

(a) 2NC — CH — CN is a stronger acid than 3 2 5CH — CO — C H .

(b) 3 2 5CH — CO — C H is more acidic than 3 2CH — CH CH= .

(c) 3CH — CH CH — OH= is more acidic than 2 2CH CH — CH — OH= .

14. H3C–C||O

–CH3 Acetone shows slow rate of reaction as compare to the H3C–C||O

–H . Why ?

15. Molecular weight of ICl (162.5) and Br2 (160) are nearly same but boiling point of ICl is 40°

higher than Br2. Why ?

16. Explain(a) N-methylpyrrolidine has a boiling of 81°C

, and piperidine has a boiling point of 106 °C .

(b) Tetrahydrofuran has a boiling point of 88 °C and its isomer cyclobutanol has a boilingpoint of 141 °C.

17. Indane 1 , 2

, 3 trione and diphenyl propane trione having high hydration constant value . Explain.

18. Cyclobutadiene exist as a dimer . Justify .

19. Write metamers of OCH2CH3

20. C4H9NO2 has different isomeric nitroalkanes . Which will form tautomers ?

21. Write the structure of two alkanes of molecular formula C8H18 having following structural features– Four 1° carbon atoms – Two 2° carbon atoms– Two 3° carbon atoms – Two asymmetric centres.

22. Write the structure of a compound having following structural features :– molecular formula = C5H9N – a five membered ring– N is 3° and asymmetric

23. Write the structure of a compound having following structural features :– molecular formula = C4H9NO – a π bond between N and O– no tautomerization

24. Structural isomers and contributing structures are different . Why ?

25. Phosgene has smaller dipolemoment than formaldehyde . Explain.

26. Write the structure of isomers C4H

6 and identify the structures that has highest dipole moment.

27. How can you explain the fact that fluoromethane (CH3F, µ = 1.81D) has a smaller dipole

moment than chloromethane (CH3Cl, µ = 1.87D), even though fluorine is more electronegnative

than chlorine ?

GOC - ISOMERISM76


28. Explain :(a) Although boron trifluoride in soluble in trimethylamine, it does soluble in triphenylamine.(b) Which CX2(X = F, Cl, Br, I) is the most stable radical and why ?

29. Sulphanilic acid although has acidic as well as basic group, it is soluble in alkali but insoluble inmineral acids. Explain.

30. Write equations for the acid base reaction that would occur when each of the following com-pounds of solution are mixed. In each case label the stronger acid and stronger base, and theweaker acid and weaker base.(a) NaNH2 is added to acetylene(b) gaseous NH3 is add to ethyl lithium in hexane

(c) C2H5OH is added to a solution of HC ≡ in liquid NH3.(d) NaH is added to H3COH

31. Cyclohexanol is more soluble in water then 1-hexanol

32. 1 , 5-Pentanediol is soluble and 1-pentanol is slightly soluble in H2O. Justify the statement.

33. 1º and 2º amides tend to exist as dimer in solid and pure liquid state.

34. Explain the following:(a) p-Chlorobenzene is more soluble in n-propyl alcohol than methyl alcohol , while

o-dichlorobenzene is less soluble in n-propyl alcohol than methanol.(b) Heterolytic cleavage requires more energy than homolytic cleavage.

35. How many isomer of molecular formla C3H

7NO are posiible while all isomer should have

‘amide’ group and one of the isomer different properties. Name that isomer and give reason ofdifferent characteristics.

36. Write down the all possible amides of formula C3H

7NO and show one among these isomers,

show exceptionally behaviour. Draw the structure of that isomers and give reason for thisexception.

37. Explain enol form of acetoacetic ester is said to be more volatile thath keto form.

38. Explain the α-methyl acetyl acetone undergoes enolization to a smaller extent than acetylacetone .

39.. Why CH3 –

O

C– CH2 –

O

C– CH3 is known as active methylene compound ?

77GOC - ISOMERISM


IIT-JEE PROBLEMS

Fill in the blanks :

1. Among the given cations , ________ is most stable . [ sec-butyl carbonium ion ; tert-butyl carbonium ion ; n-butyl carbonium ion ] [ 1981 ]

2. The compound having both sp and sp2 hybridized carbon atoms is ________ . [ Propane , propane , propadiene ] [1981 ]

3. ________ ring is most strained . (Cyclopropane , Cyclobutane , Cyclopentane) [ 1981 ]

4. The terminal carbon atom in butane ________ hybridised . [ 1985 ]

5. Isomers which are ________ mirror images are known as ________ [ superimposable , non-superimposable , enantiomers , diastereomers , epimers ]

[ 1988 ]

6. The valence atomic orbitals on carbon in silver acetylide is ________ hybridised . [ 1990 ]

7. The kind of delocalization involving sigma bond orbitals is called ________ . [ 1994 ]

8. Among PCl3, CH

3+, NH

2¯ and NF

3 , ________is least reactive towards water . [ 1997 ]

True/false :

1. Iodide is a better nucleophile than bromide . [ 1985 ]

2. An electron donating substituent in benzene orients the incoming electrophilic group to the metaposition . [ 1987 ]

3. 2 , 3 , 4-Trichloropentane has three asymmetric carbon atoms . [ 1990 ]

4. During SN1 reaction

, the leaving group leaves the molecule before the incoming group is attached

to the molecule . [ 1990 ]

Multiple Choice Questions

1. The bond order of individual carbon-carbon bonds in benzene is :(a) one (b) two(c) between one and two (d) one and two, alternately [ 1981 ]

2. Molecule in which the distance between the two adjacent carbon atoms is largest is(a) Ethane (b) Ethene (c) Ethyne (d) Benzene [ 1981 ]

3. The compound which is not isomeric with diethyl ether is(a) n-propyl methyl ether (b) butan-1-ol(c) 2-methylpropan-2-ol (d) butanone [ 1981 ]

4. Among the following, the compound that can be most readily sulphonated is(a) benzene (b) Nitrobenzene (c) toluene (d) Chlorobenzene

[ 1982 ]

5. The compound 1, 2-butadiene has :(a) only sp hybridized carbon atom (b) only sp2 hybridized carbon atoms(c) both sp and sp2 hybridized carbon atoms (d) sp, sp2 and sp3 hybridized carbon atoms

[ 1985 ]

GOC - ISOMERISM78


6. An isomer of ethanol is :(a) methanol (b) diethyl ether (c) acetone (d) dimethyl ether

[ 1987 ]

7. Out of the following compounds, which will have a zero dipole moment ?(a) 1, 1-dichloroethylene (b) cis-1, 2-dichloroethylene(c) trans-1, 2-dichloroethylene (d) None of these compounds . [ 1987 ]

8. The bond between carbon atom (1) and carbon atom (2) in compound

N C — CH = CH≡ 21 2 involves the hybrids as :

(a) sp2 and sp2 (b) sp3 and sp (c) sp and sp2 (d) sp and sp[ 1987 ]

9. The number of isomers of C6H

14 are :

(a) 4 (b) 5 (c) 6 (d) 7 [ 1987 ]

10. The Cl–Cl–Cl angle in 1,1,2,2-tetrachloroethene and tetrachloromethane respectively will be about(a) 120º & 109.5º (b) 90º & 109.5º (c) 109.5º & 90º (d) 109.5º & 120º

[ 1988 ]

11. In CH3CH

2OH, the bond that undergoes heterolytic cleavage most readily is :

(a) C − (b) C − O (c) C − H (d) O − H [ 1988 ]

12. The compound which has one isopropyl group is :(a) 2

, 2

, 3

, 3

-

tetramethylpentane (b) 2

, 2

-

dimethylpentane

(c) 2 , 2

, 3

-

trimethylpentane (d) 2

-

methylpentane [ 1989 ]

13. The C – H bond distance is the longest in :(a) C

2H

2(b) C

2H

4(c) C

2H

6(d) C

2H

2Br

2

[ 1989 ]

14. The number of sigma and pi -

bonds in 1

-

buten

-

3

-

yne are :

(a) 5 sigma & 5 pi (b) 7 sigma & 3 pi (c) 8 sigma & 2 pi (d) 5 sigma & 4 pi[ 1989 ]

15. The compound which gives the most stable carbonium ion on dehydration is :

(a) CH —CH CH OH3 2—

CH3

(b) CH —C OH3 —

CH3

CH3

(c) CH3—CH

2—CH

2—CH

2OH (d) CH —CH H3 2—C —CH3

OH

[ 1989 ]

16. The hybridization of carbon atom in C – C single bond of HC ≡ C – CH = CH is :(a) sp3–sp3 (b) sp2–sp3 (c) sp–sp2 (d) sp3–sp [ 1991 ]

17. Read the following statement and explanation and answer as per the options given below :Statement (S) : Aryl halides undergo nucleophilic substitution with ease.Explanation (E) : The carbon-halogen bond in aryl halides has partial double bond character.(a) Both S and E are true, and E is the correct explanation of S(b) Both S and E are true, and E is not the correct explanation of S(c) S is true but E is false.(d) S is false but E is true. [ 1991 ]

79GOC - ISOMERISM


18. The products of combustion of an aliphatic thiol (RSH) at 298 K are :(a) CO

2(g), H

2O (g) and SO

2(g) (b) CO

2(g), H

2O(l) and SO

2(g)

(c) CO2(l), H

2O(l) and SO

2(g) (d) CO(g), H

2O(l) and SO

2(l)

[ 1992 ]

19. Allyl isocyanide has :(a) 9σ and 4π bonds (b) 8σ and 5π bonds(c) 9σ, 3π and 2 non-bonded electrons (d) 8σ, 3π and 4 non-bonded electrons

[ 1995 ]

20. Arrange in order of decreasing trend towards SE reactions :

(I) Chlorobenzene (II) benzene (III) Anilinium chloride (IV) toluene(a) II > I > III > IV (b) III > I > II > IV (c) IV > II > I > III (d) I > II > III > IV

[ 1995 ]

21. Most stable carbonium ions is :(a) p—NO

2—C

6H

4—CH

2+ (b) C

6H

5CH

2+

(c) p—Cl—C6H

4—CH

2+ (d) p—CH

3O—C

6H

4—CH

2+ [ 1995 ]

22. In the following compounds

(I)

OH

(II)

OH

CH3

(III)

OH

NO2

(IV)

OH

NO2

The order of acidity is :(a) III > IV > I > II (b) I > IV > III > II (c) II > I > III > IV (d) IV > III > I > II

[ 1996 ]

23. Arrange the following compounds in order of increasing dipole momentI Toluene II m-dichlorobenzene III o-dichlorobenzene IV p-dichlorobenzene(a) I < II < III < IV (b) IV < III < I < II (c) III > II > I > IV (d) IV > II > I > III

[ 1996 ]

24. In the following groups :(I) — OAc (II) — OMe (III) — OSO

2Me (IV) — OSO

2CF

3

The order of leaving group ability is :(a) I < IV < II < III (b) IV < I < II < III (c) III > II > I > IV (d) II > III > IV > I

[ 1997 ]

25. Among the given compounds, the most susceptible to nucleophilic attack at the carbonyl group is :(a) MeCOCl (b) MeCHO (c) MeCOOMe (d) MeCOOCOMe

[ 1997 ]

26. In the compound CH2 = CH – CH

2 – C ≡ CH, The C

2–C

3 bond is of the type.

(a) sp – sp2 (b) sp3 – sp3 (c) sp – sp3 (d) sp2 – sp3 [ 1999 ]

27. Which of the following has the highest nucleophilicity ?(a) F¯ (b) OH¯ (c) CH

3¯ (d) NH

2¯ [ 2000 ]

28. The order of reactivities of the following alkyl halides for a SN2 reaction is :

(a) RF > RCl > RBr > RI (b) RF > RBr > RCl > RI(c) RCl > RBr > RF > RI (d) RI > RBr > RCl > RF [ 2000 ]

GOC - ISOMERISM80


29. Which of the following has the most acidic hydrogen ?(a) 3-Hexanone (b) 2, 4-Hexanedione (c) 2,5-Hexanedione (d) 2,3-Hexanedione

[ 2000 ]

30. Read the following statement and explanation and answer as per the options given below :Assertion : Phenol is more reactive than benzene towards electrophilic substitution reaction.Reason : In the case of phenol, the intermediate carbocation is more resonance stabilized.(a) If both assertion and reason are CORRECT and reason is the CORRECT explanation of the

assertion.(b) If both assertion and reason are CORRECT, but reason is NOT the CORRECT explanation

of the assertion.(c) If assertion is CORRECT, but reason is INCORRECT.(d) If assertion is INCORRECT, but reason is CORRECT. [ 2000 ]

31. The number of isomers for the compound with molecular formula C2BrClFI is :

(a) 3 (b) 4 (c) 5 (d) 6 [ 2001 ]

32. An SN2 reaction at an asymmetric carbon of a compound always gives

(a) an enantiomer of the substrate (b) a product with opposite optical rotation(c) a mixture of diastereomers (d) a single stereoisomer [ 2001 ]

33. Which of the following acids has the smallest dissociation constant ?(a) CH

3CHFCOOH (b) FCH

2CH

2COOH

(c) BrCH2CH

2COOH (d) CH

3CHBrCOOH [ 2002 ]

34. Identify the correct order of boiling point of the following compounds .(1) CH

3CH

2CH

2CH

2OH (2) CH

3CH

2CH

2CHO (3) CH

3CH

2CH

2COOH

(a) 1 > 2 > 3 (b) 3 > 1 > 2 (c) 1 > 3 > 2 (d) 3 > 2 > 1[ 2002 ]

35. Identify the correct order of reactivity in electrophilic substitution reactions of the following compounds

(1) (2)

CH3

(3)

Cl

(4)

NO2

(a) 1 > 2 > 3 > 4 (b) 4 > 3 > 2 > 1 (c) 2 > 1. > 3 > 4 (d) 2 > 3 > 1 > 4[ 2002 ]

36. Which of the following hydrocarbons has the lowest dipole moment ?

(a) C = C

CH3

H

CH3

H(b) CH

3C ≡ CCH

3

(c) CH3CH

2C≡CH (d) CH

2 = CH – C ≡ CH [ 2002 ]

37. Which of the following represents the given mode of hybridisation sp2–sp2–sp–sp from left toright ?(a) H

2C = CH – C ≡ N (b) HC ≡ C – C ≡ CH

(c) H2C = C = C = CH

2(d)

CH2

H2C [ 2003 ]

38. Among the following, the molecule with the highest dipole moment :(a) CH

3Cl (b) CH

2Cl

2(c) CHCl

3(d) CCl

4[ 2004 ]

81GOC - ISOMERISM


39. Which of the following resonating structures of 1-methoxy-1,3-butadiene is least stable ?

(a) CH – CH = CH – CH = O – CH2 3 (b) CH = CH – CH – CH = O – CH2 2 3

(c) CH CH CH = CH – O – CH2 3– – (d) CH CH CH = CH – O – CH2 3= –

[ 2005 ]

40. CH O3

CH3CH3 CH3

CH3ClH

NO2 compound on hydrolysis in aqueous acetone

will give :

(i) CH O3

CH3CH3 CH3

CH3OHH

NO2

(ii) CH O3

CH3CH3 CH3

CH3HOH

NO2

(iii) CH O3

CH3CH3 CH3

OHCH3H

NO2

(a) Mixture of (i) and (ii) (b) Mixture of (i) and (iii)(c) Only (iii) (d) Only (i) [ 2005 ]

41. Arrange the following compounds in the order of increasing boiling point(I) Hydroxy benzene (II) ortho dihydroxy benzene(III) meta dihydroxy benzene (IV) para dihydroxy benzene(a) (IV) > (III) > (II) > (I) (b) (III) > (IV) > (II) > (I)(c) (II) > (III) > (I) > (IV) (d) (I) > (II) > (III) > (IV)

[ 2006 ]

Multiple choice question . [ One or more than one correct answer(s) ]

1. Resonance structure of a molecule should have :(a) Identical arrangement of atom (b) nearly the same energy content(c) the same number of paired electrons (d) identical bonding [ 1984 ]

2. Phenol is less acidic than :(a) acetic acid (b) p-methoxyphenol (c) p-nitrophenol (d) ethanol

[ 1986 ]

3. Dipole moment is shown by :(a) 1, 4-dichlorobenzene (b) cis 1, 2-dichloroethane(c) trans 1, 2-dichloroethene (d) trans 1, 2-dichloro-2-pentene [ 1986 ]

4. Only two isomeric monochloro derivatives are possible for :(a) n-butane (b) 2, 4-dimethylpentane(c) benzene (d) 2-methylpropane [ 1986 ]

GOC - ISOMERISM82


5. Which of the following have asymmetric carbon atom ?

(a) H—C—C—H

Cl

H H

Br

(b) H—C—C—Cl

H

H H

Cl

(c) H—C—C—H

H

H H

Cl

(d) H—C—C—CH2

H

Br OH

H

[ 1989 ]

6. What is the decreasing order of strength of the bases OH¯, NH2¯, H – C ≡ C¯ and CH

3 – CH

2¯?

(a) CH3 – CH

2¯ > NH

2¯ > H – C ≡ C¯ > OH¯

(b) H – C ≡ C¯ > CH3 – CH

2¯ > NH

2¯ > OH¯

(c) OH¯ > NH2¯ > H – C ≡ C¯ > CH

3 – CH

2¯

(d) NH2¯ > H – C ≡ C¯ > OH¯ > CH

3 – CH

2¯ [ 1993 ]

7. Which of the following compounds will show geometrical isomerism ?(a) 2-Butene (b) propene (c) 1-phenylpropene (d) 2-methyl-2-butene

[ 1998 ]

8. Among the following compounds , the strongest acid is :

(a) HC ≡ CH (b) C6H

6(c) C

2H

6(d) CH

3OH [ 1998 ]

9. Tautomerism is exhibited by :

(a) CH = CH – OH (b) O O

(c) O

O

(d) O

O

[ 1998 ]

10. An aromatic molecule will :(a) have 4n π electrons (b) have (4n + 2) π electrons(c) be planar (d) be cyclic [ 1999 ]

SUBJETIVE PROBLEMS :

1. Write structural formulae for all the isomeric alcohols having the molecular formula C4H

10O.[ 1984 ]

2. Arrange the following in :(i) Increasing reactivity towards HCN

CH3CHO , CH

3COCH

3 , HCHO , C

2H

5COCH

3

(ii) n-butane, n-butanol, n-butyl chloride, isobutane in increasing order of boiling point,.(iii) Benzene, toluene, methoxybenzene, chlorobenzene in increasing order of reactivity towards

sulphonation with fuming sulphuric acid.I ClCH

2COOH , II CH

3CH

2COOH , III ClCH

2CH

2COOH ,

IV (CH3)

2CHCOOH , V CH

3COOH

(iv) Increasing reactivity in nucleophilic substitution reactionsCH

3F, CH

3I, CH

3Br, CH

3Cl [ 1985 ]

3. For nitromethane molecule, write structure(s)(a) showing significant resonance stabilization.(b) indicating tautomerism [ 1986 ]

83GOC - ISOMERISM


4. Give reasons for the following :(a) Carbon oxygen bond lengths in formic acid are 1.23Å and 1.36 Å and both the carbon oxygen

bonds in sodium formate have the same value i.e. 1.27Å.(b) Phenyl group is known to exert negative inductive effect. But each phenyl ring in biphenyl

(C6H

5 –C

6H

5) is more reactive than benzene towards electrophilic substitution.

(c) Aryl halides are less reactive than alkyl halides towards nucleophilic reagents.(d) CH

2=CH¯ is more basic than HC ≡ C¯

(e) Normally, benzene gives electrophilic substitution reaction rather than electrophilic additionreaction although it has double bonds.

[ 1986 ]

5. Discuss the hybridisation of carbon atoms in allene (C3H

4) and show the π-orbital overlaps .

[ 1999 ]

6. Which one is more soluble in diethyl ether-anhydrous AlCl3 or hydrous AlCl

3 ? Explain .

[ 2003 ]

7. Match the Ka values

Ka

(a) Benzoic acid (i) 3.3 × 10–5

(b) COOHO N2 (ii) 10.2 × 10–5

(c) COOHCl (iii) 30.6 × 10–5

(d) COOHH CO3 (iv) 6.4 × 10–5

(e) COOHH C3 (v) 4.2 × 10–5

[ 2003 ]

8.

CH2

OH

H C3

Write resonance structure of the given compound . [ 2003 ]

9. Which of the following is more acidic and why ?

H N3 , H N3

F [ 2004 ]

10. mobs

= ∑µi

iix , where µi is the diople moment of a stable conformer of the molecule ,

Z – CH2– CH

2 – Z and x

i is the mole fraction of the stable conformer .

[ Given mobs

= 1.0 D and x (Anti) = 0.82 ]Draw all the stable conformers of Z – CH

2 – CH

2 – Z and calculate the value of µ

(Gauche) .

[ 2005 ]

GOC - ISOMERISM84


ANSWERS

LEVEL -

I

1. 2. 3. 4. 5. 6. 7.

8. 9. 10. 11. 12. 13. 14.

15. 16. 17. 18. 19. 20. 21.

22. 23. 24. 25. 26. 27. 28.

29. 30. 31. 32. 33. 34. 35.

36. 37. 38. 39. 40. 41. 42.

43. 44. 45. 46. 47. 48. 49.

50. 51. 52. 53. 54. 55. 56.

57. 58. 59. 60. 61. 62. 63.

64. 65.

LEVEL -

II A

1. 2. 3. 4. 5. 6. 7.

8. 9. 10. 11. 12. 13. 14.

15. 16. 17. 18. 19. 20. 21.

22. 23. 24. 25. 26. 27. 28.

29. 30. 31. 32. 33. 34. 35.

36. 37. 38. 39. 40. 41. 42.

43. 44. 45. 46. 47. 48. 49.

50. 51. 52. 53. 54. 55. 56.

57. 58. 59. 60.

LEVEL -

II B

1. 2. 3. 4. 5. 6. 7.

8. 9. 10. 11. 12. 13. 14.

15. 16. 17. 18. 19. 20. 21.

22. 23. 24. 25. 26. 27. 28.

29. 30. 31. 32. 33. 34. 35.

36. 37. 38. 39. 40. 41. 42.

43. 44. 45. 46. 47. 48. 49.

50.

85GOC - ISOMERISM


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