Question 1

Which of the following statements best explains why alkenes exhibit cis/trans (geometric) isomerism, but alkanes do not?

Accepted Answer

Alkenes have a carbon-carbon double bond that restricts rotation, while alkanes have only single bonds allowing free rotation.

Question 2

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

$$\mathrm{CH_3CH_2CH=$$CHCH_3$$}$$

Accepted Answer

2-pentene

Question 3

What is the main reason that trans-2-butene is more stable than cis-2-butene?

Accepted Answer

Trans isomers have reduced steric interactions between substituents compared to cis isomers.

Question 4

Which of the following best describes the hybridization of the carbon atoms in ethene ($$\mathrm{C_2H_4}$$)?

Accepted Answer

Each carbon is $$\mathrm{sp^2$}$$ hybridized.

Question 5

Which of the following is the correct E/Z designation for the compound below?

$$\mathrm{CH_3CH=CHCl}$$

Accepted Answer

E-2-chloro-2-butene

Question 6

Which of the following statements about the electrophilic addition of hydrogen halides to alkenes is correct?

Accepted Answer

The hydrogen atom attaches to the carbon with fewer alkyl substituents, following Markovnikov's rule.

Question 7

Which of the following carbocations is the most stable?

Accepted Answer

Tertiary ($$\mathrm{3^\circ}) $$carbocation

Question 8

Which of the following best explains why terminal alkynes are more acidic than alkenes and alkanes?

Accepted Answer

The $$\mathrm{sp}$$ hybridized carbon in alkynes holds electrons closer, making the hydrogen more acidic.

Question 9

Which of the following is the product of the acid-catalyzed hydration of 2-methylpropene ($$\mathrm{CH_2$=C(CH_3$)_2}$$)?

Accepted Answer

tert-butanol ($$\mathrm{(CH_3$)_3COH})$$

Question 10

Which catalyst is used to selectively hydrogenate alkynes to cis-alkenes?

Accepted Answer

Lindlar's catalyst

Question 11

Which of the following best describes the mechanism of electrophilic addition to alkenes?

Accepted Answer

The pi electrons of the double bond attack the electrophile, forming a carbocation intermediate.

Question 12

Which of the following is a real-world example of an alkene acting as a plant hormone?

Accepted Answer

Ethylene ($$\mathrm{C_2H_4}) is $$used to ripen fruit such as tomatoes.

Question 13

Which of the following is the correct IUPAC name for the compound below?

$$\mathrm{HC\equiv CCH_2CH_3}$$

Accepted Answer

1-butyne

Question 14

Which of the following factors does NOT contribute to the increased stability of conjugated alkenes compared to isolated alkenes?

Accepted Answer

Conjugated alkenes are always cyclic.

Question 15

Which of the following is a correct statement about the physical properties of alkenes?

Accepted Answer

Alkenes are hydrophobic and have poor water solubility.

Question 16

Which of the following is the correct product when ethyne ($$\mathrm{HC\equiv CH}) is $$treated with sodium amide ($$\mathrm{$$NaNH_2$$}$$)?

Accepted Answer

Acetylide anion ($$\mathrm{HC\equiv C^-})$$

Question 17

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

Accepted Answer

The metal surface adsorbs hydrogen and alkene, facilitating bond breaking and formation.

Question 18

Which of the following is a correct application of Markovnikov's rule in the addition of water to propene ($$\mathrm{CH_3CH=CH_2$}$$)?

Accepted Answer

The hydroxyl group attaches to the more substituted carbon, forming 2-propanol.

Question 19

Which of the following is a real-world consequence of alkene oxidation in pharmaceuticals?

Accepted Answer

Oxidation can produce peroxides, which may cause drugs to lose pharmacological activity.

Alkenes and Alkynes: Structure, Nomenclature, Isomerism, and Reactivity

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