Question 1

Which of the following statements best explains why alkenes are classified as 'unsaturated' hydrocarbons?

Accepted Answer

Because they have fewer hydrogen atoms than the corresponding alkane due to the presence of a double bond.

Question 2

Which of the following is the correct general formula for an acyclic alkene?

Accepted Answer

$$\mathrm{C}_n\mathrm{H}_{2n}$$

Question 3

Which of the following best describes the bonding in an alkene?

Accepted Answer

A single $$\sigma$$ bond and a $$\pi$$ bond between two carbon atoms.

Question 4

Which of the following properties is NOT characteristic of alkenes?

Accepted Answer

Soluble in water

Question 5

In the hydrohalogenation of 2-methylpropene with HBr, which is the major product and why?

Accepted Answer

2-bromo-2-methylpropane, because the bromine adds to the more substituted carbon, forming the more stable carbocation intermediate.

Question 6

Which of the following best describes Markovnikov’s Rule?

Accepted Answer

The electrophile adds to the carbon of the double bond with the most hydrogen atoms.

Question 7

During the addition of HCl to 3,3-dimethyl-1-butene, a rearrangement occurs. What type of rearrangement is most likely and why?

Accepted Answer

A 1,2-methyl shift, because a methyl group moves to stabilize a tertiary carbocation.

Question 8

Which of the following is the correct product for the acid-catalyzed hydration of 1-methylcyclohexene?

Accepted Answer

2-methylcyclohexanol

Question 9

Which of the following statements about hydroboration-oxidation of alkenes is correct?

Accepted Answer

The overall addition of water is anti-Markovnikov.

Question 10

Which of the following best explains why E (trans) alkenes are generally more stable than Z (cis) alkenes?

Accepted Answer

Because E isomers have less steric strain due to bulky groups being on opposite sides.

Question 11

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 12

What is the major product when 1-butene reacts with HBr in the presence of peroxides?

Accepted Answer

1-bromobutane

Question 13

Which of the following is a nucleophile in the reaction between ethene and HBr?

Accepted Answer

Ethene ($$\mathrm{CH}_2=CH_2$)

Question 14

Which of the following best describes the mechanism of oxymercuration-reduction of alkenes?

Accepted Answer

It proceeds via a mercurinium ion intermediate, preventing rearrangements.

Question 15

How many degrees of unsaturation are present in a molecule with the formula $$\mathrm{C}_5\mathrm{H}_8$$?

Accepted Answer

2

Question 16

Which of the following is the correct E/Z designation for the following alkene: $$\mathrm{CH}_3CH=CHCH_2Br$$ where the higher priority groups are on opposite sides?

Accepted Answer

E

Question 17

Which of the following statements about the acid-catalyzed hydration of alkenes is FALSE?

Accepted Answer

The reaction is anti-Markovnikov overall.

Question 18

Which of the following is the major product when 3-methyl-1-butene reacts with HCl?

Accepted Answer

2-chloro-2-methylbutane (after a 1,2-hydride shift)

Question 19

Which of the following best describes the role of boron in the hydroboration of alkenes?

Accepted Answer

Boron acts as an electrophile due to its incomplete octet.

Question 20

Which of the following is the correct IUPAC name for a compound with two double bonds at positions 1 and 3 in a five-carbon chain?

Accepted Answer

1,3-pentadiene

Alkenes: Structure, Properties, and Reactions (Chapter 8, Part 1)

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