Question 1

Which of the following statements correctly describes the difference between alkenes and alkynes?

Accepted Answer

Alkenes contain a carbon-carbon double bond, while alkynes contain a carbon-carbon triple bond.

Question 2

Which of the following molecules is an example of a terminal alkyne?

Accepted Answer

$$CH_3C \equiv CH$$

Question 3

Which statement about cis- and trans- isomers is correct?

Accepted Answer

Cis- and trans- prefixes are used for double bonds with two different substituents.

Question 4

In the E/Z naming system, how is priority assigned to substituents on a double bond?

Accepted Answer

Priority is given to the group with the highest atomic number.

Question 5

Which of the following best describes the stability trend of alkenes?

Accepted Answer

The more substituted the alkene, the more stable it is.

Question 6

Why do cycloalkenes with five or fewer carbons exist only in the cis form?

Accepted Answer

Trans cycloalkenes with small rings are too strained to exist at room temperature.

Question 7

Which reagent is commonly used to prepare sodium ethoxide ($$NaOEt$$)?

Accepted Answer

$$EtOH + Na$$

Question 8

In an E2 elimination reaction, which product is favored according to Zaitsev’s rule?

Accepted Answer

The most substituted alkene.

Question 9

Which condition favors an E2 elimination over substitution for a 1° alkyl halide?

Accepted Answer

Use of a bulky, strong base such as potassium t-butoxide.

Question 10

Which base would most likely result in Hofmann elimination (formation of the least substituted alkene)?

Accepted Answer

$$t-$$BuOK$$ (potassium t-butoxide)$$

Question 11

Which of the following is true about the stereochemistry of E2 eliminations?

Accepted Answer

The base must remove a proton from the opposite side and in the same plane as the leaving group (anti-coplanar).

Question 12

Which type of alcohol is the easiest to dehydrate under acid-catalyzed conditions?

Accepted Answer

3° alcohol

Question 13

What is the role of sodium amide ($$NaNH_2) in $$alkyne chemistry?

Accepted Answer

It deprotonates terminal alkynes to form acetylide anions.

Question 14

Which reaction mechanism involves the formation of a carbocation intermediate?

Accepted Answer

E1 elimination

Question 15

Which of the following statements about the hydrogenation of alkenes is correct?

Accepted Answer

Hydrogenation of alkenes is a syn addition.

Question 16

Which reagent is used to selectively hydrogenate an alkyne to a cis-alkene?

Accepted Answer

Lindlar's catalyst

Question 17

Which of the following statements is true regarding the synthesis of alkynes from vicinal dibromides?

Accepted Answer

Two E2 eliminations are required to form the alkyne.

Question 18

Which of the following nucleophiles will react with a terminal acetylide anion via an SN2 mechanism?

Accepted Answer

A methyl or 1° alkyl halide

Question 19

Which of the following is a real-world application of organic synthesis discussed in the materials?

Accepted Answer

Production of drugs and medicines

Question 20

Which elimination mechanism is common in biological systems and involves a resonance-stabilized carbanion intermediate?

Accepted Answer

ElcB elimination

Alkenes & Alkynes: Structure, Isomerism, and Elimination Reactions

Study Guide - Practice Questions