ISOMERISM

1. Which is the pair of geometrical isomers :

Cl–CH2 CH2–COOH Cl–CH2 CH2–COOH
(i) C=C (ii) C=C
Br CH3 CH3 Br

Br CH2–COOH CH3COO Br
(iii) C=C (iv) C=C 7
Cl–CH2 CH3 CH3 CH2–Cl
(1) i & ii (2) i & iii (3) iii & iv (4) i & iv

Cl

2. How many geometrical isomers are possible for :

I Br
(1) 2 (2) 3 (3) 4 (4) 8

3. Which will not show geometrical isomerism :

(1) Maleic acid (2) Fumaric acid (3) Cinnamic acid (4) Salicylic acid

4. Which of the following has highest number of geometrical isomers.

Br

(1) (2) (3) (4)

Br Br

5. Total number of position isomers of trichlorocyclohexane which can show geometrical isomerism.
(1) 2 (2) 3 (3) 4 (4) 6
6. The total number of stereoisomers of 2,3 -butanediol are :
(1) four (2) two (3) six (4) three.
7. The most stable form of meso-tartaric acid is
(1) Gauche form (2) Anti form
(3) Fully eclipsed form (4) Partially eclipsed

8. Which of the following molecules possess a plane of symmetry?

(1) (2) (3) (4) More than one of these

9. Select correct order of stability of different forms of 1-Chloro-4-iodo cyclohexane.

(I) (II) (III) (IV)

(1) IV > III > I > II (2) IV > I > III > II (3) III > II > I > IV (4) II > I > III > IV

10. Which of the following statement is incorrect ?

(1) Diastereomers can be chiral.
 (2) Diastereomers can be achiral.
(3) Enantiomers have similar physical and chemical properties always.
(4) Presence of plane of symmetry confirms optical inactivity.

11. Which type of isomerism is shown by 2,3-Dichlorobutane?

(1) Tautomerism (2) Optical (3) Geometrical (4) Functional isomerism

12. Increasing order of stability among the three main conformations of 2-Fluoroethanol is :
(1) Eclipse, Gauche, Anti (2) Gauche, Eclipse, Anti
(3) Eclipse, Anti, Gauche (4) Anti, Gauche, Eclipse

13. The unusually stable three membered unsaturated compound, Feist acid was found to be chiral in nature. Its
structure is :

(1) (2)

(3) (4)

14. Which of the following depict the same stereoisomer ?

(1) I and II (2) I and III (3) II and III (4) I, II and III

15. The total number of chiral centres present in the artificial sweetener Aspartam are

(1) 1 (2) 2 (3) 3 (4) 4

16. Which pair is identical ?

(1) H and H (2) and

Cl Cl
 Br Br
C C
(3) and (4) H CH3 and H3C H
Cl Cl

17. Identify the relation between molecules given in Newman and Fischer projections.

(1) Identical (2) Enantiomers (3) Diastereomers (4) Conformers

18. The correct IUPAC name of D-Glucose is :

(D-Glucose)

(1) (2D,3D,4L,5D)-2, 3,4,5,6-pentahydroxyhexanal

(2) D-2,3,4,5,6-pentahydroxyhexanal
(3) 6-oxo-(2D,3L,4D,5D)-2,3,4,5,6-pentahydroxohexane
(4) (2D,3L,4D,5D)-2,3,4,5,6-pentahydroxyhexanal

19. Which of the following species will be optically active ?

C 2H5
|
(1) (2) H3 C  N  C 3H7 (3) (4)

20. Which of the following compounds exhibits stereoisomerism ?

(1) 2-methylbutene-1 (2) 3-methylbutyne-1
(3) 3-methylbutanoic acid (4) 2-methylbutanoic acid

21. Identify the chiral species among the following :

(1) (2) (3) (4)

22. The isomeric alcohol which has a chiral carbon atom is :

(1) n-butyl alcohol (2) iso-butyl alcohol (3) sec-butyl alcohol (4) tert-butyl alcohol
23. The configurations of the carbon atoms C2 and C3 in the following compound are respectively.

(1) R, R (2) S, S (3) R, S (4) S, R

24. Which of the following will not show geometrical isomerism ?

(1) CH3–NN–CH=CH2 (2)

(3) CH3–CH=N–OH (4) Cl–CH=C=CH–Cl

25. The racemic mixture in liquid/gaseous state will have

(1) Same boiling point as that of its pure enantiomer.
(2) Same refractive index as that of its pure enantiomer.
(3) Same density as that of its pure enantiomer.
(4) All of the above.

26. True statement(s) regarding the given molecule is /are :

CH2–OH
H OH
HO H
H OH
H OH
CH2–OH
(1) This is optically inactive.
(2) If the last chiral carbon configuration is charged then it is converted from dextro to laevo.
(3) By changing the configuration at C3 or C4 carbon, it is converted into meso compound.
(4) Its all diastereomers have zero optical rotation.

27. Most stable conformation of 1,4-Di(tert-butyl) cyclohexane is

(1) chair (2) Boat (3) Half chair (4) Twist boat

28. The two compounds (I) and (II) are related as :

COOH COOH
HO H OH H
H
H OH OH
and
COOH COOH
(I) (II)

(1) Enantiomers (2) Anomers (3) Diastereomers (4) Identical

29. How many stereoisomers of shikonin (a drug for healing of wounds) are possible & how many of them are
optically active ?
 (1) 4, 2 (2) 4, 4 (3) 8, 4 (4) 16, 4

30. Which of the following compounds is capable of showing geometircal, optical and conformational isomerism.

(1) (2) H2C  CH – CH – CH3

|
OH
(3) CH3–CH=CH–CH2–CH2–OH (4) H2C=CH–CH2–OH
 PART 2
SECTION-1 : (Only One option correct Type)

1. is a Fischer projection of one of______stereoisomers?

(A) 2 (B) 4 (C) 8 (D) 12

2. Which of the following has maximum number of two-fold axis of symmetry.

(A) Ethylene (B) Cyclopropane
(C) Cyclobutane (D) Benzene

3. The following compounds are :

Cl Cl Cl Cl

Cl Cl Cl Cl
(I) (II)

(A) Enantiomer (B) Identical (C) Diastereomer (D) Geometrical isomer

4. Which conformation of Bicyclo [2, 2, 2]-octane is more stable ?

(A) Chair (B) Half Boat (C) Boat (D) Twisted boat

5. In the given energy graph for cyclohexane, the point “B” represent.

(A) Chair conformation (B) Half chair conformation

 (C) Twist boat conformation (D) Boat conformation

6. Identify the most stable stereoisomer :

(A) (B)

CH3 CH3

(C) (D)
CH3

7. Molecular formula of smallest ester which contain one chiral carbon is :

(A) C4H8O2 (B) C5H12O (C) C6H12O2 (D) C5H10O2

8. Which of the following has/have potential energy diagram for conformations closely resembling to ethane.
(I) 2,2-Dimethylpropane (II) 2,3-Dimethylbutane
(III) 2,2,3-Trimethylbutane (IV) 2,2-Dimethylbutane
(A) I, III, IV (B) I, II, IV (C) I, II, III (D) II, III, IV

Section-2 : (One or More than one options correct Type)

9. Which statement(s) is/are correct for the given reaction and compounds.

COOH
OH C O Ester
+ H


(d + ) one isomer only O

(A) Two esters are formed. (B) All the esters are chiral.
(C) Both esters are diastereomers. (D) Racemic mixture is formed as a product.

10. Intra-molecular H-bonding is possible in which of the following.

(A) cis-cyclohexane-1,2-diol (B) trans-cyclohexane-1,2-diol
(C) cis-cyclohexane-1,3-diol (D) cis-cyclohexane-1,4-diol

11. Which of the following statement(s) is/are correct ?

(A) Anti conformation of H2N–CH2–CH2–NH2 is always more stable than its Gauche confromation.
(B) Gauche conformation of HO–CH2–CH2F is more stable than its anti conformation at room temperature.
(C) On increasing temperature, dipole moment of pure Cl–CH2–CH2–Cl increases.
(D) In case of 1,4-Dihydroxycyclohaxane twisted boat conformer is most stable.

12. Which of the following compounds can show Optical isomerism as well as geometrical isomerism?

(A) (B)
 (C) (D)

13. Which of the following compounds can show geometrical isomerism.

Cl Cl Cl Cl
* * * *
R C S R C R
(A) (B)
C C
CH3 H CH3 H

CH3 CH3
(C) (D) C
H
H

14. Which of the following statement(s) is/are true about the following compounds ?

(A) () and () are identical (B) () and () are geometrical diastereomers
(C) () and () are structural isomers. (D) () and () are structural isomers.

Section-3 : (Single/ Double Integer Value Correct Type.)

15. An organic compound P exists in two enantiomeric forms, which have specific optical rotation values [] = ±
100°. The optical rotation of a mixture of these two enantiomers is – 50°. Calculate the percentage of that
enantiomer which is in lower concentration in the mixture.

16. Total number of meso forms possible for 1,2,3,4-Tetrachlorocyclobutane.

17. If “A” is total number of meso compounds and “B” is total number of optically active isomers ; then find (A+B)
for

18. Sum of total no. of stereoisomers (A) and total no. of fractions (B) for the compound is

19. How many of the following carbonyl compound will give two products after reaction with NH 2OH :
 (i) (ii) (iii)

(iv) (v) (vi)

(vii) (viii) (ix) CH3–CH=O

20. Total number of stereoisomers of truxillic acid are :

SECTION-4 : Comprehension Type (Only One options correct)

Paragraph For Questions 21 to 22

An unknown substance (P) shows optical activity. This optical activity disappears on treatment of (P) with
acidified KMnO4 (which produces Q), or with heated copper (which produces R). (P) produces silver mirror
with Tollen’s reagent, thereby producing (S). (S) is chiral. Based on this information, answer the following
questions :

21. (P) may be -

O O
H3C
(A) (B)
OH OH

H3C OH
H3C OH

(C) (D)
H3C OH
OH

22. Number of stereoisomers possible for (P) is –

(A) 2 (B) 3 (C) 4 (D) 8

SECTION-5 : Matching List Type (Only One options correct)

23. Match the compounds of Column-I with their relationship with mentioned in Column-II.
 Column-I Column-II

P. 1. Geometrical isomer

Q. 2. Conformation

R. 3. Positional isomer

S. 4. Identical

Code :
P Q R S
(A) 4 2 3 1
(B) 1 2 4 3
(C) 2 1 3 4
(D) 1 2 3 4