Question 1

Which of the following statements best describes the difference between constitutional isomers and stereoisomers?

Accepted Answer

Constitutional isomers have the same molecular formula but different connectivity; stereoisomers have the same molecular formula and connectivity but different spatial arrangement.

Question 2

Which historical experiment led to the discovery of molecular chirality?

Accepted Answer

The separation of tartaric acid crystals by hand under a microscope, revealing mirror-image forms with different optical properties.

Question 3

A carbon atom bonded to four different groups is called:

Accepted Answer

A chiral center

Question 4

How many stereoisomers are possible for a molecule with three chiral centers?

Accepted Answer

$$2^3 = 8$

Question 5

Which of the following is true about enantiomers?

Accepted Answer

They have identical physical properties except for their interaction with chiral environments and optical activity.

Question 6

What is the correct sequence of steps for assigning R/S configuration to a chiral center?

Accepted Answer

Assign priorities, rotate so the lowest priority is away, determine direction, assign R/S.

Question 7

A compound with chiral centers but is achiral due to a plane of symmetry is called:

Accepted Answer

A meso compound

Question 8

Which of the following best explains why thalidomide caused birth defects?

Accepted Answer

One enantiomer was sedative, while the other was teratogenic, causing birth defects.

Question 9

Which of the following is true about the optical rotation of a racemic mixture?

Accepted Answer

It has an optical rotation of zero.

Question 10

When prioritizing groups for R/S assignment, how are double and triple bonds treated according to the Cahn-Ingold-Prelog system?

Accepted Answer

Double bonds count as two single bonds, triple bonds count as three single bonds.

Question 11

Which instrument is used to measure the rotation of plane-polarized light by chiral compounds?

Accepted Answer

Polarimeter

Question 12

If a chiral compound has a specific rotation $$[\alpha] = +23.1$$^{\circ}$$, what is the specific rotation of its enantiomer?

Accepted Answer

$$[\alpha] = -23.1$$^{\circ}$$

Question 13

Which of the following molecules is most likely to be chiral?

Accepted Answer

A carbon atom bonded to four different groups.

Question 14

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

Accepted Answer

Boiling point

Question 15

A molecule has two chiral centers. How many stereoisomers are possible, assuming no meso forms?

Accepted Answer

$$2^2 = 4$

Question 16

Which of the following best describes a diastereomer?

Accepted Answer

A stereoisomer that is not a mirror image of its counterpart.

Question 17

Which of the following would NOT result in a chiral center?

Accepted Answer

A carbon atom bonded to two identical groups.

Question 18

Which of the following is a correct statement about meso compounds?

Accepted Answer

They have chiral centers but are achiral due to an internal plane of symmetry.

Question 19

Which of the following best describes the effect of a racemic mixture on plane-polarized light?

Accepted Answer

It does not rotate the light.

Question 20

In the Cahn-Ingold-Prelog system, how is priority assigned when two groups attached to a chiral center have the same atomic number?

Accepted Answer

By comparing the atomic number of the next atoms along the chain.

Stereoisomerism and Stereochemistry: Foundations and Applications

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