Question 1

Which of the following statements best explains why rotation around the carbon–carbon double bond in ethylene is restricted?

Accepted Answer

Because the pi bond is formed by the sideways overlap of unhybridized p orbitals, which would be disrupted by rotation.

Question 2

Given the molecular formula $$\mathrm{C_4H_8}$$, how many elements of unsaturation does this compound have?

Accepted Answer

$$1$$

Question 3

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

$$	ext{(Image: 2-bromo-5-heptene)}$$

Accepted Answer

2-bromo-5-heptene

Question 4

Which of the following compounds can exhibit cis/trans (geometric) isomerism?

Accepted Answer

2-butene

Question 5

According to the Cahn-Ingold-Prelog priority rules, which of the following groups has the highest priority?

Accepted Answer

$$-C(CH_3$)_3$$

Question 6

Arrange the following in order of increasing dipole moment: ethylene, vinyl chloride, propene, trans-1-chloropropene.

Accepted Answer

ethylene \u003c propene \u003c vinyl chloride \u003c trans-1-chloropropene

Question 7

Which of the following alkenes is the most stable based on heat of hydrogenation data?

Accepted Answer

2-methylpropene

Question 8

Which of the following best describes the E2 elimination mechanism?

Accepted Answer

It is a one-step, bimolecular process where a strong base abstracts a proton as the leaving group departs.

Question 9

When 2-bromobutane is treated with sodium ethoxide, which alkene is formed in the greatest amount according to Zaitsev’s rule?

Accepted Answer

2-butene (major, both E and Z isomers)

Question 10

Which of the following statements about the E1 and E2 mechanisms is correct?

Accepted Answer

E1 reactions are more likely to undergo rearrangements than E2 reactions.

Question 11

Which product is favored when tert-butyl bromide reacts with sodium ethoxide in ethanol?

Accepted Answer

2-methylpropene (E2 product)

Question 12

Which of the following bases would most likely lead to the Hofmann product in an elimination reaction?

Accepted Answer

tert-butoxide ion

Question 13

Which of the following is a characteristic of the E2 elimination mechanism?

Accepted Answer

It requires a coplanar (usually anti) arrangement of the leaving group and the hydrogen being abstracted.

Question 14

Which of the following alcohols will dehydrate most rapidly under acid-catalyzed conditions?

Accepted Answer

tert-butyl alcohol ($$\mathrm{(CH_3$)_3COH})$$

Question 15

Which of the following reagents cannot be used to dehydrate 2-methyl-2-propanol to an alkene?

Accepted Answer

$$\mathrm{HCl}$$

Question 16

Which of the following best describes the major product of the acid-catalyzed dehydration of 2-methyl-2-butanol?

Accepted Answer

2-methyl-2-butene

Question 17

Which of the following statements about Zaitsev’s rule is correct?

Accepted Answer

The most substituted alkene is usually the major product in elimination reactions.

Question 18

Which of the following would most likely proceed via an E1 mechanism?

Accepted Answer

2-bromo-2-methylbutane in ethanol (heat)

Question 19

Which of the following is NOT a promoting factor for the E2 mechanism?

Accepted Answer

A weak base

Structure and Preparation of Alkenes: Elimination Reactions

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