CHEMISTRY WITH M.R.
KHAN
CLASS TEST - 04
TOPIC - ISOMERISM
1. The incorrect statement regarding chirality 6. CH 3 CHCl CH 2 CH 3 has a chiral centre.
is:
Which one of the following represents its
(1) The product obtained by SN2 reaction of
R- configuration?
haloalkane having chirality at the reactive site
shows inversion of configuration.
(2) Enantiomers are superimposable mirror image (1) (2)
of each other
(3) A racemic mixture shows zero optical rotation.
(4) SN1 reaction yield 1 : 1 mixture of both
enantiomers
(3) (4)
2. Two possible stereo-structures of
CH3CHOHCOOH, which are optically active,
are called ? 7. Assertion : Alkanes can have an infinite number
(1) Diastereomers of conformations.
(2) Enantiomers Reason : In configurational isomerism, the
(3) Mesomers isomers are distinct individual substances
(4) Atropisomers (1) Both A and R are correct and R is the correct
3. Assertion : Meso-tartaric acid is optically explanation of A.
inactive. (2) Both A and R are correct but R is not the
Reason : Meso-tartaric acid contains two correct explanation of A.
asymmetrical carbon atoms. (3) Both A and R are not correct
(1) Both A and R are correct and R is the correct (4) A is not correct but R is correct
explanation of A. 8. With respect to the conformers of ethane,
(2) Both A and R are correct but R is not the which of the following statements is true?
correct explanation of A. (1) Bond angle changes but bond length remains
(3) Both A and R are not correct same
(4) A is not correct but R is correct (2) Both bond angle and bond length change
4. Which of the following acids does not exhibit
(3) Both bond angle and bond length remains
optical isomerism?
same
(1) Maleic acid
(2) -Amino acids (4) Bond angle remains same but bond length
(3) Lactic acid changes
(4) Tartaric acid 9. The correct statement regarding the
5. Which of the following combinations comparison of staggered and eclipsed
amongst the four Fischer projections conformation of ethane, is :
represents the same absoluteconfiguration (1) The staggered conformation of ethane is less
S? stable than eclipsed conformation, because
staggered conformation has torsional strain
CH3 (2) The elipsed conformation of ethane is more
CH CH 2
H OH stable than staggered conformation, because
(I) (II) CH 3 OH eclipsed conformation has no torsional strain
CH CH 2 (3) The eclipsed conformation of ethane is more
H
stable than staggered conformation even
OH H though the eclipsed conformation has
CH CH 2
torsional strain
(III) H CH 3 (IV) HO
(4) The staggered conformation of ethane is more
CH CH 2 CH 3 stable than eclipsed conformation, because
(1) I & II staggered conformation has no torsional strain
(2) III & IV 10. How many stereoisomers are possible for
(3) I & III 2,3- butandiol ?
(4) II & IV (1) 1 (2) 3
(3) 2 (4) 4
16. In the Fischer projection below, what are the
configuration of the two asymmetric centers?
CO 2 H
11. Given and
H CH 3
H OH
I and II are CH 2CH 2OH
(1) A pair of optical isomers
(2) Identical (1) 2R,3R (2) 2R, 3S
(3) A pair of conformers (3) 2S,3R (4) 2S, 3S
(4) A pair of geometrical isomers
CH 3 CH 3
12. In the following the most stable conformation
of n-butane is : H Br Br H
17. Br H H Br
(1) (2) CH 3 CH 3
(A) (B)
CH 3
H Br
(3) (4)
H Br
13. The restricted rotation about carbon - carbon CH 3
double bond in 2-butene is due to :
(1) Overlap of one s-and sp2 - hybridized (C)
orbitals If optical rotation of compound (A) is 26.4
(2) Overlap of two sp2- hybridized orbitals then what is the optical rotation for
(3) Overlap of one p - and one sp2 - hybridized compound (B) and (C) respectively
orbitals (1) 26.4 , Zero
(4) Sideways overlap of two p - orbitals. (2) Zero, 26.4
14. The structure of 2S,3S - (3) Zero, Zero
(4) 26.4 , 26.4
CH3CHClCH(CH3 )C2 H5 is
18. Which one of the following compounds is
CH 3 CH 3 capable of existing in a meso form?
(1) 3,3-Dibromopentane
(1) Cl H (2) H Cl
(2) 3-Bromo-2-pentanol
CH 3 H CH 3 H (3) 2,3-Dibromopentane
(4) 2,4-Dibromopentane
C2H5 C2H5 19. The two enantiomers of a compound can be
separated by
CH 3 (1) fractional disillation
CH 3
(2) fractional crystallization
H Cl Cl H (3) chromatographic techniques
(4) the use of suitable optically active reagent
(3) H CH 3 (4) H CH 3
20. The stability of conformations of
cyclohexane decreases in the order :
C2H5 C2H5
(1) chair > haif chair > boat > twist boat
15. The maximum number of possible optical (2) chair > twist boat > boat > half chair
isomers in l-bromo-2-methyl cyclobutane is: (3) chair > boat > twist boat > half chair
(1) 2 (2) 4 (4) boat > twist boat > chair > half chair
(3) 8 (4) 16
21. Which of the following is true? 27. Which of the following is E configuration
(i) The observed rotation of a solution of an according to E and Z system:
optically active compound doubles on (1)
doubling the concentration of the
solution (2)
(ii) The observed rotation of a solution of an (3)
optically active compound doubles on
doubling the length of the tube of (4)
polarimeter.
(iii) Both of the above statement are true 28. The optically active molecule is:
also for specific rotation COOMe COOMe
(iv) None of the above statement is true for HO H H OH
specific rotation (1) HO H (2) H OH
(1) (i), (ii) and (iii) (2) (i), (ii) and (iv)
(3) only (i) (4) only (ii) COOMe COOH
22. Increasing order of stability among the three COOMe COOH
main conformations (i.e., eclipse, anti, D OH H OH
gauche) of 2-fluoroethanol is : (3) D OH (4) H OH
(1) eclipse, gauche, anti
(2) gauche, eclipse, anti COOMe COOH
(3) eclipse, anti, gauche 29. Which of the following does not have a trans
(4) anti, gauche, eclipse isomer?
23. The two enantiomers of a compound have H 3C H
(1) different direction of rotation but the same
(1) C C
amount of rotation
H H
(2) same direction of rotation but different amount
of rotation
Cl Cl
(3) same direction of rotation as well same amount
C C
of rotation
H
(4) different direction of rotation as well as (2) H
different amount of rotation
H 3C H 3C
24. Meso compounds do not show optical
activity because: (3) C C
(1) they contain plane of symmetry H H
(2) they do not contain chiral carbon atoms
(3) they do not contain plane of symmetry Cl Cl
(4) of external compensation
25. The isomeric deuterated bromide with (4)
molecular formula C4H8DBr having two H H
chiral carbon atoms is : 30. The number of pairs of enantiomers for the
(1) 2-bromo-3-deuterobutane compound 3-chloro-2-pentanol is
(2) 2-bromo-1-deuterobutane (1) 1 (2) 2
(3) 2-bromo-1-deutero-2-methylpropane (3) 3 (4) 4
(4) 2-bromo-2-deuterobutane 31. Number of primary amines of the formula
26. Maleic acid and fumaric acid are the forms
C4 H 11N is:
of :
(1) Chain isomers (1) 1 (2) 2
(2) Conformations (3) 8 (4) 4
(3) Geomertical isomers 32. A compound is formed by substitution of two
(4) Optical isomers chlorine for two hydrogens in propane. The
number of possible isomeric compounds is:
(1) 2 (2) 3
(3) 4 (4) 5
33. Which one of the following pairs represents 39. Which of the following can not exist in ‘syn’
stereoisomerism ? and ‘anti’ forms?
(1) Chain isomerism and rotational isomerism (1) C 6 H5 N N OH
(2) Structural isomerism and geometrical
(2) C6 H5 N N C 6 H 5
isomerism
(3) Linkage isomerism and geometrical (3) C6 H5 CH N OH
isomerism (4) C6 H 5 2 C N OH
(4) Optical isomerism and geometrical isomerism
40. Cis-2-butene and trans-2-butene are not:
34. Out of the following , the alkene that (1) configurational isomers
exhibits optical isomerism is : (2) diastereomers
(1) 2-methyl -2- pentene (3) conformational isomers
(2) 3-methyl -2- pentene (4) geometrical isomers
(3) 4-methyl -1- pentene 41. Total number of stereo isomers possible for
(4) 3-methyl -1- pentene the compound
35. The number of stereoisomers possible for a H3 C CH CH CH CH CH CH Ph
compound of the molecular formula : (1) 6
CH3 CH = CH CH(OH) CH3 is : (2) 4
(1) 3 (3) 8
(4) 2
(2) 4
42. What is the molecular formula for the alkane
(3) 2 of smallest molecular weight which possesses
(4) 6 a stereogenic center ?
36. Which of the following compounds will (1) C4H10
exhibit geometrical isomerism? (2) C6H14
(1) 1, 1- Diphenyl - 1- propene (3) C5H12
(2) 1- Phenyl - 2- butene (4) C7H16
(3) 3- Phenyl -1- butene 43. (i) CH 2 CH CH 2 CH CH 2
(4) 2- Phenyl - 1- butene (ii) CH 2 CH CH CH CH CH 3
37. Which of the following compounds contain
(iii) CH3 CH CH CH CH CH 3
stereocenters ?
(I) 1-Chloropentane The numbers of possible geometric isomers
(II) 2-Chloropentane for the above compounds respectively are:
(III) 3-Chloropentane (1) 0, 2, 4
(IV)1,2-Dichloropentane (2) 2, 2, 4
(1) I,II (3) 0, 3, 3
(2) I,III (4) 0, 2, 3
(3) III,IV 44. D - Glucose has how many optical isomers ?
(4) II,IV (1) 4
38. Select ‘trans’ isomer among the following: (2) 16
(3) 8
Br (4) 12
(1) 45. The correct decreasing priority of
Br
ligands NO 2 C N, NH 2 and CH 2 NH 2
Br in absolute configuration of an enantiomer is
(2) (1) NO2 NH2 C N CH2 NH2
Br
(2) NO 2 C N NH 2 CH 2 NH 2
Br (3) NH 2 NO 2 C N CH 2 NH 2
(3) (4) NH 2 NO 2 CH 2 NH 2 C N
Br
(4) None
