Chirality Quiz
Questions: 16 · 10 minutes
1. Two compounds are non-superimposable mirror images of each other. What is their relationship?
Constitutional isomers
Enantiomers
Conformers
Diastereomers
2. A compound has three independent tetrahedral stereogenic centers, with no internal symmetry and no other stereogenic elements. What is the maximum number of configurational stereoisomers?
8
6
4
3
3. Which property is identical for pure enantiomers measured under the same achiral conditions?
Boiling point
Direction of optical rotation
Interaction with every chiral receptor
Retention time on a suitably chosen chiral chromatography column
4. Which description best defines a meso compound?
An achiral compound with stereogenic centers and internal symmetry
An equal mixture of two enantiomers
A chiral compound that has a plane of symmetry
An achiral compound with no stereogenic centers
5. Which molecule is achiral because its candidate tetrahedral carbon has two identical substituents?
2-Butanol
2-Propanol, CH₃–CH(OH)–CH₃
Bromochlorofluoromethane, CHBrClF
Lactic acid, CH₃–CH(OH)–CO₂H
6. In an R/S assignment, the lowest-priority group points away from you and the path from priority 1 to 2 to 3 is clockwise. What is the configuration?
E
S
R
Z
7. Which structural feature can produce axial chirality even when no tetrahedral carbon bears four different substituents?
Any isolated carbon–carbon single bond
A carbonyl group with two different attachments
A terminal alkene with two hydrogen atoms
An allene with two different substituents on each terminal carbon
8. Which carbon in 2-butanol, CH₃–CH(OH)–CH₂–CH₃, is a stereogenic center?
Carbon 1, the terminal CH₃ carbon nearest OH
Carbon 3, the CH₂ carbon
Carbon 4, the other terminal CH₃ carbon
Carbon 2, the carbon bearing OH
9. What makes a molecular structure chiral?
It lacks every type of molecular symmetry.
It contains at least one double bond.
It has a nonzero formal charge.
It cannot be superimposed on its mirror image.
10. An SN2 reaction replaces a leaving group at a stereogenic carbon through backside attack. If the priority ordering of the relevant substituents is otherwise unchanged, what stereochemical result is expected at that carbon?
Retention of configuration
Formation of an equal enantiomer mixture
Inversion of configuration
Loss of all molecular stereochemistry
11. A tetrahedral carbon is bonded to CH₃, CH₂CH₃, OH, and H. How should this carbon be classified?
It is not stereogenic because it is bonded to hydrogen.
It is achiral because two substituents contain carbon.
It is stereogenic because its four substituents are different.
It is a geometric-isomerism center because it has four single bonds.
12. For a molecule with two stereogenic centers and no internal symmetry, what is the relationship between its (R,R) and (S,S) forms?
They are identical.
They are constitutional isomers.
They are diastereomers.
They are enantiomers.
13. A sample contains equal amounts of two enantiomers and is measured under ordinary achiral conditions. What net optical rotation is expected?
A positive rotation determined by the R enantiomer
Zero, because the equal and opposite rotations cancel
A negative rotation determined by the S enantiomer
Twice the rotation of either pure enantiomer
14. A tetrahedral carbon is bonded to H, D, T, and Cl, where D and T are hydrogen isotopes. What follows from treating isotopes as distinct under the sequence rules?
The carbon is not stereogenic because H, D, and T are all hydrogen.
The carbon is stereogenic because all four attached substituents are distinguishable.
The carbon is stereogenic only if the molecule carries a charge.
The carbon must have E or Z configuration.
15. At one tetrahedral stereogenic center, two substituents are interchanged while the other two remain fixed. Assuming the priority order itself does not change, what happens?
The configuration is inverted from R to S or from S to R.
The configuration stays the same.
The center becomes a double bond.
The molecule necessarily becomes meso.
16. Two stereoisomers have the same connectivity and differ at one, but not all, of their stereogenic centers. They are not mirror images. How are they related?
They are resonance structures.
They are enantiomers.
They are diastereomers.
They are constitutional isomers.