Question 1

Which of the following best describes a tertiary (3°) carbon atom?

Accepted Answer

A carbon atom bonded to three other carbon atoms.

Question 2

What is the IUPAC name for the following compound: $$\mathrm{CH_3CH_2CH_2CH_3}$$?

Accepted Answer

Butane

Question 3

Which conformation of ethane is the most stable and why?

Accepted Answer

Staggered conformation, because it minimizes torsional strain.

Question 4

In the Newman projection of butane, which conformation corresponds to the lowest potential energy?

Accepted Answer

Anti conformation ($$180^\circ$$ dihedral angle between the two methyl groups)

Question 5

Which of the following statements about cyclopropane is correct?

Accepted Answer

It has significant angle strain because its bond angles are $$60^\circ$$, far from the ideal $$109.5^\circ.$$

Question 6

Which of the following best explains why cyclohexane adopts a chair conformation?

Accepted Answer

To minimize both angle strain and torsional strain.

Question 7

A monosubstituted cyclohexane is most stable when the substituent is in which position?

Accepted Answer

Equatorial position, because it minimizes steric strain.

Question 8

Which of the following is true regarding cis-trans isomerism in cycloalkanes?

Accepted Answer

Cis-trans isomerism arises because the carbon-carbon single bonds in rings cannot freely rotate.

Question 9

What is the ideal bond angle for a carbon atom with $$sp^3$$ hybridization?

Accepted Answer

$$109.5^\circ$$

Question 10

Which of the following best describes torsional strain?

Accepted Answer

Destabilization caused by the eclipsing of bonds on neighboring atoms.

Question 11

A molecule of 2-bromopropane contains a bromine atom attached to which type of carbon?

Accepted Answer

A secondary (2°) carbon.

Question 12

Which of the following is the correct IUPAC name for the compound with the structure $$\mathrm{CH_3CH_2CH_2Cl}$$?

Accepted Answer

1-Chloropropane

Question 13

Which of the following statements about the chair–chair interconversion (ring flip) in cyclohexane is correct?

Accepted Answer

Axial positions become equatorial and equatorial positions become axial after a ring flip.

Question 14

Which of the following best describes steric strain?

Accepted Answer

Repulsion between groups that are so close together that their electron clouds experience interference.

Question 15

Which of the following cycloalkanes has the least angle strain?

Accepted Answer

Cyclopentane

Question 16

In the conformational energy diagram of ethane, what is the energy difference between the staggered and eclipsed conformations?

Accepted Answer

$$12.6\ \mathrm{kJ/mol}$$ ($$3.0\ \mathrm{kcal/mol})$$

Question 17

Which of the following is a correct statement about the stability of the boat conformation of cyclohexane?

Accepted Answer

It is less stable than the chair conformation due to increased steric and torsional strain.

Question 18

A student is asked to draw the most stable conformation of methylcyclohexane. Where should the methyl group be placed?

Accepted Answer

In the equatorial position to minimize steric strain.

Question 19

Which of the following best describes the relationship between the cis and trans isomers of 1,2-dimethylcyclopentane?

Accepted Answer

They are stereoisomers with the same connectivity but different spatial arrangements.

Question 20

Which of the following is the correct IUPAC name for the compound shown below?

A six-membered ring with a single methyl group attached.

Accepted Answer

Methylcyclohexane

Structure and Stereochemistry of Alkanes: Chapter 3

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