Question 1

Which of the following statements best describes a chiral molecule?

Accepted Answer

A molecule that cannot be superimposed on its mirror image.

Question 2

How many stereoisomers are possible for a molecule with 3 chiral centers, assuming no meso forms?

Accepted Answer

$$2^3 = 8$

Question 3

Which of the following is true about enantiomers?

Accepted Answer

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

Question 4

A carbon atom is considered a chiral center if:

Accepted Answer

It is bonded to four different groups.

Question 5

Which of the following best describes a diastereomer?

Accepted Answer

A stereoisomer that is not a mirror image of another stereoisomer.

Question 6

Which property can be used to separate a mixture of diastereomers but not enantiomers?

Accepted Answer

Boiling point

Question 7

What is the maximum number of stereoisomers for a molecule with 2 chiral centers?

Accepted Answer

$$2^2 = 4$

Question 8

Which of the following statements about optical activity is correct?

Accepted Answer

A compound that rotates plane-polarized light is said to be optically active.

Question 9

According to the Cahn-Ingold-Prelog priority rules, which atom is assigned the highest priority when attached to a chiral center?

Accepted Answer

The atom with the highest atomic number.

Question 10

Which of the following is true about meso compounds?

Accepted Answer

They contain chiral centers but are achiral as a whole.

Question 11

A racemic mixture contains:

Accepted Answer

Equal amounts of two enantiomers.

Question 12

Which of the following is NOT a property that differs between diastereomers?

Accepted Answer

Molecular formula

Question 13

Which statement about the relationship between the sign of optical rotation and the R/S configuration is correct?

Accepted Answer

There is no correlation; the sign must be determined experimentally.

Question 14

Which of the following is the correct definition of a stereocenter?

Accepted Answer

Any atom at which the interchange of two groups gives a stereoisomer.

Question 15

A molecule with two chiral centers is found to have only three stereoisomers. What is the most likely explanation?

Accepted Answer

One of the stereoisomers is a meso compound.

Question 16

Which of the following is true about Fischer projections?

Accepted Answer

They are used only for chiral carbons.

Question 17

When assigning R/S configuration, what is the correct procedure after assigning priorities to the four groups attached to the chiral center?

Accepted Answer

Orient the molecule so the lowest priority group is at the back, then trace from highest to lowest priority.

Question 18

Which of the following statements is correct regarding the physical properties of enantiomers?

Accepted Answer

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

Question 19

Which of the following compounds would be expected to be optically inactive?

Accepted Answer

A meso compound

Question 20

A student is given a sample of (R)-2-bromobutane and measures its specific rotation as $$[\alpha]^D_{25} = -23.1^\circ. $$What would be the expected specific rotation for a pure sample of (S)-2-bromobutane?

Accepted Answer

$$[\alpha]^D_{25} = +23.1^\circ$$

Stereochemistry: Chirality, Isomerism, and Optical Activity

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