Name: __________________________ Date: _____________


Isomerism

 

1.
How many constitutional isomers of C3H8 are possible?
A.
1
B.
2
C.
3
D.
4

2.
C4H10 has how many constitutional isomers?
A.
7
B.
5
C.
2
D.
1


3.
C5H12 has ______ constitutional isomers.
A.
2
B.
3
C.
4
D.
5


4.
Which compound does not have two or more constitutional isomers?
A.
C3H7Cl
B.
C2Cl6
C.
C3H6Cl2
D.
C5H12


5.
Which compounds are isomers?
(1)
(2)
(3)
A.
1 and 2 only
B.
1 and 3 only
C.
2 and 3 only
D.
1, 2, and 3


6.
Which compounds are isomers?
(1)
(2)
(3)
A.
1 and 2 only
B.
1 and 3 only
C.
2 and 3 only
D.
1, 2, and 3


7.
These two structures represent:
           (CH3)2CH-CH(CH3)2
A.
the same compound
B.
different compounds that are constitutional isomers
C.
different compounds that are stereoisomers
D.
different compounds that are not isomers


8.
These two compounds are:
               (CH3)2CHCH2CH3
A.
the same
B.
different, but constitutional isomers of each other
C.
stereoisomers
D.
different, and not isomers of each other


9.
These two compounds:
   
A.
are the same.
B.
are different, and they are constitutional isomers.
C.
are different, and they are cis-trans isomers
D.
are different, and they are not isomers.


10.
Which compound cannot have cis- and trans-isomers?
A.
2-hexene
B.
1,2-dimethylbenzene
C.
1-chloro-2-methylcyclohexane
D.
1,2-dichlorocyclopentane


11.
Which compound has cis- and trans-isomers?
A.
2-pentyne
B.
1-pentyne
C.
1-chloro-2-methylcyclohexane
D.
1,2-dichlorobenzene


12.
How many ketones that are constitutional isomers of pentanal are possible?
A.
1
B.
2
C.
3
D.
4


13.
Which statement is true?
A.
Constitutional isomers have the same connectivity but differ in their configurations.
B.
Enantiomers are stereoisomers that are superimposable mirror images of each other.
C.
Diastereomers are stereoisomers that are enantiomers, that is, they are not mirror images of each other.
D.
Stereoisomers have the same connectivity but differ in their configurations.


14.
Which of the following objects is achiral?
A.
a coffee cup with the name MARY imprinted on it
B.
a table fork with no engraving or other markings
C.
a TV set
D.
a shoe


15.
Which of these structures can exist as a pair of enantiomers?
 
I
 
II
 
III
 
IV
 
A.
I only
B.
II and IV only
C.
III and IV only
D.
I and IV only


16.
This molecule has _____ tetrahedral stereocenters.
A.
0
B.
1
C.
2
D.
3


17.
This molecule has _____ tetrahedral stereocenters.
A.
0
B.
1
C.
2
D.
3


18.
Which statement about this molecule it true?
A.
The molecule is achiral.
B.
The molecule has one trigonal stereocenter.
C.
The molecule has one trigonal and one tetrahedral stereocenter.
D.
The molecule has one tetrahedral stereocenter.


19.
Which statement is true about these compounds?
 
I.
II.
 
 
A.
I and II represent the same compound.
B.
I and II are different compounds that are constitutional isomers.
C.
I and II are different compounds that are enantiomers.
D.
I and II are different compounds that are not isomers.


20.
Which statement is false?
A.
Enantiomers are a pair of stereoisomers whose molecules are nonsuperimposable mirror images.
B.
The only difference in physical properties of a pair of enantiomers is the direction of rotation of plane-polarized light.
C.
Enantiomers show large differences in chemical reactivity toward achiral compounds.
D.
Enantiomers show large differences in chemical reactivity in reactions catalyzed by chiral enzymes.


21.
Which statement is true about these compounds?
 
X.
Y.
 

I) X and Y are both optically active
II) X and Y are enantiomers
III) X and Y are diastereomers
A.
I only
B.
II only
C.
I and III only
D.
I and II only


22.
Which statement is true about these compounds?
 
X.
Y.
 

I) Neither X nor Y is optically active.
II) X and Y are enantiomers.
III) X and Y are diastereomers.
A.
I only
B.
II only
C.
III only
D.
I and III only


23.
Which compound has one pair of trans enantiomers and one pair of cis enantiomers?
A.
3-methylcyclohexanone
B.
1,1-dimethylcyclopentane
C.
2-methyl-1,3-cyclohexanedione
D.
1-hydroxy-2-methylcyclohexane


24.
Which of the following statements is true?
 
I.
II.
 
 
A.
I and II are the same compound.
B.
I and II are different compounds that are constitutional isomers.
C.
I and II are different compounds that are diastereomers.
D.
I and II are different compounds that are enantiomers.


25.
Which statement about these compounds is true?
 
I.
II.
 
 
A.
I and II represent the same compound.
B.
I and II are different compounds that are constitutional isomers.
C.
I and II are different compounds that are enantiomers.
D.
I and II are different compounds that are not isomers.


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