Question 1

How many stereoisomers of 2,4-dimethylpentane, (CH3)2CHCH2CH(CH3)2, exist?

Accepted Answer

A)  1 
B)  2 
C)  3 
D)  4 
A)  1 
B)  2 
C)  3 
D)  4

Question 2

Which of the following compounds is/are chiral?

Accepted Answer

A)  only 1 
B)  only 1 and 2 
C)  only 2 and 3 
D)  1, 2 and 3 
A)  only 1 
B)  only 1 and 2 
C)  only 2 and 3 
D)  1, 2 and 3

Question 3

How much of the R enantiomer is present in 10 g of a mixture which has an enantiomeric excess of 60% of the R isomer?

Accepted Answer

A)  2 g 
B)  4 g 
C)  6 g 
D)  8 g 
A)  2 g 
B)  4 g 
C)  6 g 
D)  8 g

Question 4

How many isomers (constitutional and stereoisomers) exist for dimethylcyclohexane?

Accepted Answer

A)  3 
B)  5 
C)  6 
D)  9 
A)  3 
B)  5 
C)  6 
D)  9

Question 5

How many stereocenters are present in trans-2-butene? ​

Accepted Answer

A)  1 
B)  2 
C)  3 
D)  0 
A)  1 
B)  2 
C)  3 
D)  0

Question 6

Which of the following structures is different from the other three?

Accepted Answer

A)  1 
B)  2 
C)  3 
D)  4 
A)  1 
B)  2 
C)  3 
D)  4

Question 7

How many stereoisomers of 2,3-dimethylbutane, (CH3)2CHCH(CH3)2, exist?

Accepted Answer

A)  1 
B)  2 
C)  3 
D)  4 
A)  1 
B)  2 
C)  3 
D)  4

Question 8

How many stereoisomers of 3-chloro-2-methylbutane, (CH3)2CHCHClCH3, exist?

Accepted Answer

A)  1 
B)  2 
C)  3 
D)  4 
A)  1 
B)  2 
C)  3 
D)  4

Question 9

A solution of 0.1 g/mL of a pure R enantiomer in a 1 dm polarimeter rotates plane polarized light by +4.8°. What is the rotation observed on this solution in a 2 dm polarimeter?

Accepted Answer

A)  +2.4° 
B)  +4.8° 
C)  +9.6° 
D)  +19.2° 
A)  +2.4° 
B)  +4.8° 
C)  +9.6° 
D)  +19.2°

Question 10

Complete the following Newman projection so that it represents (2R,3S)-2,3-dibromobutane.

Accepted Answer

The answer of Complete the following Newman projection so that...

Question 11

Complete the following diagram so that it represents (S)-2-butanol.

Accepted Answer

The answer of Complete the following diagram so that it...

Question 12

The specific rotation of the S-enantiomer of a compound is -120º. What is the enantiomeric excess of a sample of the compound that has a measured specific rotation of -30º.

Accepted Answer

ee = 25% o

Question 13

What is the relationship between the following pair of structures?

Accepted Answer

A)  They are enantiomers 
B)  They are diastereomers 
C)  The are constitutional isomers 
D)  They are identical 
A)  They are enantiomers 
B)  They are diastereomers 
C)  The are constitutional isomers 
D)  They are identical

Question 14

Of the compounds listed below, only 2 has a chiral centers. 1.$\quad$$\mathrm{OH}$
$\quad$$\quad$|
$\mathrm{CH}_{3} \mathrm{CHCH}_{3}$

2.$\quad$$\mathrm{Br}$
$\quad$$\quad$|
$\mathrm{CH}_{3} \mathrm{CHCHCH}$
$\quad$$\quad$$\quad$$\quad$|
$\quad$$\quad$$\quad$$\mathrm{CH}_{3}$

3.$\quad$$\mathrm{CH}_{3}$
$\quad$$\quad$|
$\mathrm{CH}_{3} \mathrm{CHCHCH}$
$\quad$$\quad$$\quad$$\quad$|
$\quad$$\quad$$\quad$$\mathrm{CH}_{3}$

Accepted Answer

A) True 
 B)False

Question 15

The absolute configurations around C-2 and C-3 in the following Fischer projection are, respectively, ____. (Enter the two configurations separated by a comma.)

Accepted Answer

The answer of The absolute configurations around C-2 and C-3...

Question 16

Which of the following structures have a plane of symmetry?

Accepted Answer

A)  only 1 and 2 
B)  only 2 and 4 
C)  only 3 and 4 
D)  1, 2, 3 and 4 
A)  only 1 and 2 
B)  only 2 and 4 
C)  only 3 and 4 
D)  1, 2, 3 and 4

Question 17

Which of the following statements regarding optical rotation is not true?

Accepted Answer

A)  All (+) enantiomers are dextrorotatory. 
B)  All R enantiomers are dextrorotatory. 
C)  All (−) enantiomers rotate plane-polarized light in a counterclockwise direction. 
D)  All (+) and (−) enantiomers rotate plane-polarized light in opposite directions. 
A)  All (+) enantiomers are dextrorotatory. 
B)  All R enantiomers are dextrorotatory. 
C)  All (−) enantiomers rotate plane-polarized light in a counterclockwise direction. 
D)  All (+) and (−) enantiomers rotate plane-polarized light in opposite directions.

Question 18

The specific rotation of enantiomers have the same magnitude.

Accepted Answer

A) True 
 B)False

Question 19

How many chiral centers are there in the following molecule (the naturally occurring stereoisomer is the male hormone testosterone)?

Accepted Answer

A)  Three 
B)  Four 
C)  Six 
D)  Seven 
A)  Three 
B)  Four 
C)  Six 
D)  Seven

Question 20

A pure sample of the R enantiomer of a compound has a specific rotation, [α], of +20°. A solution containing 0.2 g/mL of a mixture of enantiomers rotates plane polarized light by −2° in a 1 dm polarimeter. What is the enantiomeric excess (%ee) of the mixture?

Accepted Answer

A)  25% R 
B)  40% S 
C)  50% S 
D)  70% R 
A)  25% R 
B)  40% S 
C)  50% S 
D)  70% R

Exam 3: Stereoisomerism and Chirality

How many stereoisomers of 2,4-dimethylpentane, (CH3)2CHCH2CH(CH3)2, exist?

Which of the following compounds is/are chiral?

How much of the R enantiomer is present in 10 g of a mixture which has an enantiomeric excess of 60% of the R isomer?

How many isomers (constitutional and stereoisomers) exist for dimethylcyclohexane?

How many stereocenters are present in trans-2-butene? ​

Which of the following structures is different from the other three?

How many stereoisomers of 2,3-dimethylbutane, (CH3)2CHCH(CH3)2, exist?

How many stereoisomers of 3-chloro-2-methylbutane, (CH3)2CHCHClCH3, exist?

A solution of 0.1 g/mL of a pure R enantiomer in a 1 dm polarimeter rotates plane polarized light by +4.8°. What is the rotation observed on this solution in a 2 dm polarimeter?

Complete the following Newman projection so that it represents (2R,3S)-2,3-dibromobutane.

Complete the following diagram so that it represents (S)-2-butanol.

The specific rotation of the S-enantiomer of a compound is -120º. What is the enantiomeric excess of a sample of the compound that has a measured specific rotation of -30º.

What is the relationship between the following pair of structures?

The absolute configurations around C-2 and C-3 in the following Fischer projection are, respectively, ____. (Enter the two configurations separated by a comma.)

Which of the following structures have a plane of symmetry?

Which of the following statements regarding optical rotation is not true?

The specific rotation of enantiomers have the same magnitude.

How many chiral centers are there in the following molecule (the naturally occurring stereoisomer is the male hormone testosterone)?

A pure sample of the R enantiomer of a compound has a specific rotation, [α], of +20°. A solution containing 0.2 g/mL of a mixture of enantiomers rotates plane polarized light by −2° in a 1 dm polarimeter. What is the enantiomeric excess (%ee) of the mixture?

Covalent Bonding and Shapes of Molecules

Alkanes and Cycloalkanes

Acids and Bases

Alkenes: Bonding, Nomenclature, and Properties

Reactions of Alkenes

Alkynes

Haloalkanes, Halogenation, and Radical Reactions

Nucleophilic Substitution and Beta-Elimination

Alcohols

Ethers, Epoxides, and Sulfides

Infrared Spectroscopy

Nuclear Magnetic Resonance Spectroscopy

Mass Spectrometry

An Introduction to Organometallic Compounds

Aldehydes and Ketones

Carboxylic Acids

Functional Derivatives of Carboxylic Acids

Enolate Anions and Enamines

Dienes, Conjugated Systems, and Pericyclic Reactions

Benzene and the Concept of Aromaticity

Reactions of Benzene and Its Derivatives

Amines

Catalytic Carbon-Carbon Bond Formation

Carbohydrates

Lipids

Amino Acids and Proteins

Nucleic Acids

Organic Polymer Chemistry

Filters

How many stereoisomers of 2,4-dimethylpentane, (CH₃)₂CHCH₂CH(CH₃)₂, exist?

How many stereocenters are present in trans-2-butene?

How many stereoisomers of 2,3-dimethylbutane, (CH₃)₂CHCH(CH₃)₂, exist?

How many stereoisomers of 3-chloro-2-methylbutane, (CH₃)₂CHCHClCH₃, exist?