Question 1

Which of the following statements best explains why cis-2-butene is less stable than trans-2-butene?

Accepted Answer

Cis-2-butene has greater steric repulsion between the methyl groups on the same side of the double bond.

Question 2

Which of the following is the correct IUPAC name for the compound with the structure $$\mathrm{CH_2$=CHCH_2CH_3}$$?

Accepted Answer

1-butene

Question 3

When ethylene ($$\mathrm{CH_2$=CH_2$}) $$reacts with HCl, what is the major product and what type of reaction mechanism is involved?

Accepted Answer

Chloroethane via a polar addition mechanism involving a carbocation intermediate.

Question 4

Which of the following best describes the role of a catalyst in a chemical reaction?

Accepted Answer

It lowers the activation energy, increasing the reaction rate without being consumed.

Question 5

Which of the following statements about Markovnikov's rule is correct?

Accepted Answer

In the addition of HX to an unsymmetrical alkene, the hydrogen atom attaches to the carbon with more hydrogens already attached.

Question 6

Which of the following is the correct sequence of steps in the mechanism for the acid-catalyzed hydration of an alkene?

Accepted Answer

Protonation of the alkene, formation of a carbocation, nucleophilic attack by water, deprotonation.

Question 7

Which of the following best describes the product and stereochemistry of the halogenation of cyclohexene with $$\mathrm{Br_2$} in an $$inert solvent?

Accepted Answer

Trans-1,2-dibromocyclohexane via anti addition.

Question 8

Which of the following statements about conjugated dienes is correct?

Accepted Answer

Conjugation is possible when double bonds are separated by a single bond, allowing for delocalization of $$\pi$$ electrons.

Question 9

Which of the following is a correct statement about the resonance structure of benzene?

Accepted Answer

Benzene is best represented as a resonance hybrid of two Kekulé structures, with delocalized $$\pi$$ electrons.

Question 10

Which of the following substituents is an ortho-para director in electrophilic aromatic substitution?

Accepted Answer

$$\mathrm{-$$OCH_3$$}$$

Question 11

Which of the following best describes a meso compound?

Accepted Answer

A compound with chiral centers that is achiral due to an internal plane of symmetry.

Question 12

Which of the following statements about the separation of a racemic mixture is correct?

Accepted Answer

A racemic mixture can be separated by converting enantiomers into diastereomers using a chiral resolving agent, then separating them by physical methods.

Question 13

Which of the following is true regarding the addition of $$\mathrm{H_2$} to an $$alkyne using Lindlar's catalyst?

Accepted Answer

It produces a cis-alkene via syn addition.

Question 14

Which of the following best describes the difference between enantiomers and diastereomers?

Accepted Answer

Enantiomers are non-superimposable mirror images; diastereomers are stereoisomers that are not mirror images.

Question 15

Which of the following is the correct application of the Cahn-Ingold-Prelog rules for assigning E/Z configuration?

Accepted Answer

Assign priorities to the groups attached to each carbon of the double bond; if the higher priority groups are on opposite sides, the isomer is E.

Question 16

Which of the following best explains why electrophilic aromatic substitution (EAS) occurs instead of electrophilic addition in benzene?

Accepted Answer

EAS preserves the aromaticity of benzene, which is highly stabilized by resonance.

Question 17

Which of the following is the correct product of the reaction of 1,3-butadiene with HBr at low temperature (kinetic control)?

Accepted Answer

3-bromo-1-butene (1,2-addition product)

Question 18

Which of the following statements about optical activity is correct?

Accepted Answer

A chiral compound rotates plane-polarized light, and this can be measured using a polarimeter.

Question 19

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

Accepted Answer

A species that donates an electron pair to an electrophile.

Question 20

Which of the following best describes the structure of an allylic carbocation?

Accepted Answer

A carbocation adjacent to a double bond, stabilized by resonance.

Comprehensive Study Guide: Alkenes, Alkynes, Aromatic Compounds, and Stereochemistry

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