Question 1

Which of the following statements best describes a constitutional isomer?

Accepted Answer

Compounds with the same molecular formula but different connectivity of atoms.

Question 2

Which projection formula is most useful for visualizing the staggered and eclipsed conformations of ethane?

Accepted Answer

Newman projection

Question 3

A compound contains two asymmetric carbon atoms, each bonded to four different groups. How many possible optical isomers can exist for this compound?

Accepted Answer

$$2^2 = 4$

Question 4

Which of the following is true about a racemic mixture?

Accepted Answer

It is optically inactive due to equal amounts of both enantiomers.

Question 5

Which of the following is a requirement for a molecule to be optically active?

Accepted Answer

It must contain at least one asymmetric (chiral) carbon atom.

Question 6

Which type of isomerism is observed in 2-butene due to restricted rotation around the double bond?

Accepted Answer

Geometrical isomerism

Question 7

In the Cahn-Ingold-Prelog (R/S) system, how is the configuration of a chiral center determined?

Accepted Answer

By assigning priorities based on atomic number and observing the sequence from highest to lowest priority.

Question 8

Which of the following statements about meso compounds is correct?

Accepted Answer

Meso compounds are optically inactive due to an internal plane of symmetry.

Question 9

Which of the following is true regarding the staggered conformation of ethane?

Accepted Answer

It has lower energy due to minimized repulsion between hydrogen atoms.

Question 10

Which graphical representation is best suited for showing the three-dimensional arrangement of atoms in chiral molecules?

Accepted Answer

Fischer projection

Question 11

Which of the following is NOT allowed when manipulating a Fischer projection of a molecule with one asymmetric carbon?

Accepted Answer

Exchanging one pair of groups joined to the chiral carbon (causes inversion of configuration)

Question 12

Which of the following best describes diastereomers?

Accepted Answer

Stereoisomers that are not mirror images and differ at one or more chiral centers

Question 13

Which of the following reactions is an example of syn-addition to an alkene?

Accepted Answer

Catalytic hydrogenation with $$\mathrm{H}_2/\mathrm{Ni}$$

Question 14

Which statement is correct regarding the optical activity of a chiral molecule?

Accepted Answer

It can rotate plane-polarized light either to the right (dextrorotatory) or to the left (levorotatory).

Question 15

Which of the following is true about geometrical isomerism in alkenes?

Accepted Answer

It arises due to restricted rotation around the double bond.

Question 16

Which of the following is the correct method to assign E/Z configuration to a double bond?

Accepted Answer

Compare the atomic numbers of the substituents on each carbon and assign E if the higher priority groups are on opposite sides.

Question 17

Which of the following is a functional group isomer pair?

Accepted Answer

C$$_2H$_5OH $$and CH$$_3$$OCH$$_3$$

Question 18

Which of the following statements about the resolution of racemic mixtures is correct?

Accepted Answer

Resolution separates enantiomers from a racemic mixture.

Question 19

Which of the following is true about the Fischer projection formula for chiral molecules?

Accepted Answer

Vertical lines represent bonds going behind the plane.

Question 20

Which of the following is a correct statement about the relationship between configuration and conformation?

Accepted Answer

Conformation refers to the spatial arrangement of atoms that can be changed by rotation around single bonds.

Stereochemistry: Classification, Representation, and Chemical Reactions

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