Question 1

Which of the following statements best explains why the C=C double bond in ethene is shorter and stronger than a C–C single bond in ethane?

Accepted Answer

The double bond consists of one sigma and one pi bond, resulting in greater electron density between the carbons.

Question 2

Given the structure below, what is the correct IUPAC name for the compound?

A nine-carbon chain with a double bond between C3 and C4, an ethyl group at C7, methyl groups at C5 and C6, and a propyl group at C5.

Accepted Answer

7-ethyl-5,6-dimethyl-5-propylnon-3-ene

Question 3

Which of the following cycloalkenes requires a cis/trans label in its name?

Accepted Answer

Cyclopentene

Question 4

Which statement correctly describes the difference between cis and trans isomers of alkenes?

Accepted Answer

Cis isomers have substituents on the same side of the double bond, while trans isomers have them on opposite sides.

Question 5

Using the Cahn-Ingold-Prelog rules, which of the following has the highest priority when assigning E/Z configuration to an alkene carbon?

Accepted Answer

A chlorine atom

Question 6

What is the configuration of (E)-2-chlorobut-2-ene?

Accepted Answer

The higher priority groups are on opposite sides of the double bond.

Question 7

Which of the following statements about alkene stability is correct?

Accepted Answer

Trans alkenes are generally more stable than cis alkenes due to reduced steric interactions.

Question 8

Which effect explains why more substituted alkenes are more stable than less substituted ones?

Accepted Answer

Hyperconjugation

Question 9

During an E2 elimination reaction, which product is favored according to Zaitsev's Rule?

Accepted Answer

The most substituted alkene

Question 10

Which of the following conditions would favor the formation of the less substituted alkene in an E2 elimination?

Accepted Answer

Using a bulky base such as t-BuOK

Question 11

Why is the anti-coplanar transition state preferred in E2 eliminations?

Accepted Answer

It allows for maximum overlap of orbitals during bond breaking and formation.

Question 12

Which intermediate is formed during acid-catalyzed dehydration of alcohols to alkenes?

Accepted Answer

A carbocation

Question 13

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

Accepted Answer

Tertiary alcohol

Question 14

Which of the following best describes the role of a transition metal catalyst in alkene hydrogenation?

Accepted Answer

It provides a surface for the H–H bond to break and facilitates syn addition of hydrogen.

Question 15

In the addition of HBr to propene, which product is favored according to Markovnikov's Rule?

Accepted Answer

2-bromopropane

Question 16

Which sequence of reagents would you use to achieve anti-Markovnikov hydration of an alkene?

Accepted Answer

1) BH$$_3$$, THF; 2) H$$_2O$_2/$$NaOH

Question 17

Which product is formed when Br$$_2 is $$added to cyclohexene at room temperature?

Accepted Answer

A trans-1,2-dibromocyclohexane

Question 18

Which reagent is commonly used for the selective allylic bromination of alkenes?

Accepted Answer

N-bromosuccinimide (NBS)

Question 19

Which hybridization is found in the carbons of a C≡C triple bond in ethyne?

Accepted Answer

sp

Question 20

Which of the following statements about terminal alkynes is correct?

Accepted Answer

Terminal alkynes have a pK$$_a$$ around 25, making them more acidic than alkenes and alkanes.

Alkenes and Cycloalkenes: Structure, Nomenclature, and Bonding

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