Question 1

Which of the following statements best describes a functional group in organic chemistry?

Accepted Answer

A section of an organic molecule that consists of atoms other than carbon and hydrogen, and is responsible for much of the molecule's chemical reactivity and physical properties.

Question 2

Which of the following molecules contains a chiral center?

Accepted Answer

A carbon atom bonded to four different substituents.

Question 3

Which of the following is true about enantiomers?

Accepted Answer

They rotate plane-polarized light by equal amounts but in opposite directions.

Question 4

A racemic mixture contains:

Accepted Answer

An equal mixture of d-(+) and l-(–) enantiomers, resulting in no net optical rotation.

Question 5

Which of the following best describes a constitutional isomer?

Accepted Answer

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

Question 6

Which of the following functional groups is present in both amino acids and proteins?

Accepted Answer

Amide

Question 7

A molecule has the following groups attached to a central carbon: Br, F, OH, and H. Using the Cahn-Ingold-Prelog rules, what is the configuration if the priorities (1 = Br, 2 = F, 3 = OH, 4 = H) increase in a clockwise direction with H pointing away from you?

Accepted Answer

R (rectus)

Question 8

Which of the following statements about thalidomide is correct?

Accepted Answer

The R-isomer is bioactive, while the S-isomer causes birth defects.

Question 9

Which of the following is NOT a common way to represent organic molecules?

Accepted Answer

Atomic absorption spectrum

Question 10

Which of the following best explains why enantiomers can have different biological effects?

Accepted Answer

They interact differently with chiral environments such as enzymes and receptors.

Question 11

Which of the following is a property of a molecule with a plane of symmetry?

Accepted Answer

It is achiral and will not rotate plane-polarized light.

Question 12

Which of the following functional groups is found in the molecule shown below? (Refer to the cortisol structure in the images)

Accepted Answer

Ketone, alcohol, and alkene

Question 13

Which of the following statements about the R/S system is correct?

Accepted Answer

It describes the absolute configuration of a chiral center based on atomic number priorities.

Question 14

Which of the following is a correct application of the Cahn-Ingold-Prelog priority rules?

Accepted Answer

Assigning higher priority to the group with the highest atomic number directly attached to the chiral center.

Question 15

Which of the following best describes the relationship between butane and 2-methylpropane?

Accepted Answer

They are constitutional isomers.

Question 16

Which of the following is NOT a functional group?

Accepted Answer

Methyl

Question 17

Which of the following is true about the interaction of enantiomers with plane-polarized light?

Accepted Answer

One enantiomer rotates light clockwise (dextrorotatory), the other anticlockwise (levorotatory).

Question 18

Which of the following is a real-world example of the importance of stereochemistry in pharmaceuticals?

Accepted Answer

The use of thalidomide, where one enantiomer is therapeutic and the other is teratogenic.

Question 19

Which of the following is a correct statement about amino acids in biological systems?

Accepted Answer

Only the L-form of amino acids is used in proteins.

Question 20

Which of the following best describes the difference between a chiral and an achiral molecule?

Accepted Answer

An achiral molecule is superimposable on its mirror image.

Molecular Shapes, Functional Groups, and Stereoisomerism in Organic Chemistry

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