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A Structure Recognition Problem

Problem 1.
Examine the following formulas and select those pairs that satisfy the following conditions:
Be sure to enter two letters (and only two) in each answer box, unless you select F. In the second and third parts more than one answer is possible.

A
Wedge-bond structure of 2-methylpentane, (CH3)2CH-CH2-CH2CH3
B
Newman projection of 2-methylpentane, an eclipsed/staggered conformation
C
Zig-zag structure of 2,3-dimethylbutane, (CH3)2CH-CH(CH3)2
D
Wedge zig-zag structure of 2-methylpentane in a different conformation
E
Newman projection of 2,3-dimethylbutane
F
No formulas meet the
designated condition.
Which are identical in all respects? ...
Which are conformational isomers? ..
Which are constitutional isomers? ....

Problem 2.
Examine the following formulas and select those pairs that satisfy the following conditions:
Be sure to enter two letters (and only two) in each answer box. In the second and fourth parts more than one answer is possible.

A
Chair conformation of cis-1,4-dibromocyclohexane, one Br axial and one equatorial
B
Chair conformation of cis-1,3-dibromocyclohexane with both Br equatorial
C
Ring-flipped chair of cis-1,4-dibromocyclohexane, one Br axial and one equatorial
D
Chair conformation of trans-1,4-dibromocyclohexane with both Br axial (diaxial)
E
Chair conformation of trans-1,4-dibromocyclohexane with both Br equatorial (diequatorial)
F
Ring-flipped chair of cis-1,3-dibromocyclohexane with both Br axial (diaxial)
Which are identical in all respects? ....
Which are configurational isomers? ...
Which are conformational isomers? ...
Which are constitutional isomers? .....

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