Question 1

Which of the following best describes constitutional isomers?

Accepted Answer

Compounds with the same molecular formula but different bonding arrangements.

Question 2

Which structural feature is necessary for a molecule to exhibit cis–trans isomerism?

Accepted Answer

Presence of a carbon–carbon double bond with two different groups attached to each carbon.

Question 3

Which of the following molecules can exhibit optical isomerism?

Accepted Answer

CH3CH2CHClCH3

Question 4

A molecule with two chiral centers can have a maximum of how many stereoisomers?

Accepted Answer

4

Question 5

Which of the following statements about enantiomers is correct?

Accepted Answer

Enantiomers have identical physical properties except for their interaction with plane-polarized light.

Question 6

Which compound below is achiral?

Accepted Answer

CH3CH2CO2H

Question 7

What is the correct formula for calculating the maximum number of stereoisomers for a molecule with n chiral centers?

Accepted Answer

$$2^n$$

Question 8

Which of the following is true about meso compounds?

Accepted Answer

They have a plane of symmetry and are optically inactive.

Question 9

Which of the following best explains why cis–trans isomerism does not occur in 1-butene?

Accepted Answer

Both carbons of the double bond have identical groups attached.

Question 10

Which of the following statements about optical activity is correct?

Accepted Answer

A chiral compound rotates plane-polarized light.

Question 11

Which of the following is a real-life example of the biological importance of stereoisomers?

Accepted Answer

Only one enantiomer of L-dopa is effective in treating Parkinson’s disease.

Question 12

Which of the following is the correct Cahn-Ingold-Prelog rule for assigning priority to substituents on a chiral center?

Accepted Answer

Assign priority based on decreasing atomic number.

Question 13

Which of the following best describes diastereomers?

Accepted Answer

Stereoisomers that are not mirror images and have different physical properties.

Question 14

Which of the following statements about Fischer projections is correct?

Accepted Answer

A 180° rotation of a Fischer projection does not change the molecule.

Question 15

Which of the following is true about the physical properties of enantiomers?

Accepted Answer

They have identical melting points and densities.

Question 16

Which of the following is a correct statement about the effect of cis–trans isomerism in retinal and vision?

Accepted Answer

Absorption of light causes cis-11-retinal to convert to trans-retinal, triggering a signal for vision.

Question 17

Which of the following is a requirement for a carbon atom to be a chiral center?

Accepted Answer

It must be bonded to four different atoms or groups.

Question 18

Which of the following is true about racemic mixtures?

Accepted Answer

They contain equal amounts of both enantiomers and are optically inactive.

Question 19

Which of the following best describes the relationship between the R/S configuration and optical rotation (+/–)?

Accepted Answer

The sign of optical rotation is not directly correlated to the R/S designation.

Isomerism and Stereochemistry: Constitutional Isomers, Cis-Trans Isomers, and Optical Isomerism

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