Question 1

Which statement best explains why alkenes are generally more reactive than alkanes in addition reactions?

Accepted Answer

Alkenes contain a carbon-carbon double bond with diminished p orbital overlap, making the π bond easier to break and thus more reactive.

Question 2

What is the degree of unsaturation for a molecule with the formula $$\mathrm{C}_5\mathrm{H}_{10}$$?

Accepted Answer

1

Question 3

Which of the following best describes the hybridization and geometry of the carbon atoms in ethylene ($$\mathrm{C}_2\mathrm{H}_4$$)?

Accepted Answer

sp$$^2$$ hybridized, trigonal planar geometry

Question 4

Which of the following is true about cis-trans isomerism in alkenes?

Accepted Answer

Cis-trans isomerism occurs in disubstituted alkenes when each carbon of the double bond has two different groups attached.

Question 5

Given the molecule 2-butene, which statement correctly describes the difference between its cis and trans isomers?

Accepted Answer

The cis isomer has both methyl groups on the same side of the double bond, while the trans isomer has them on opposite sides.

Question 6

Which rule is used to assign priorities to groups attached to the carbons of a double bond for E/Z isomerism?

Accepted Answer

Groups are prioritized by the atomic number of the atom directly attached to the double bond carbon.

Question 7

In the addition of HX to an alkene, which product is favored according to Markovnikov's rule?

Accepted Answer

The hydrogen atom adds to the carbon with more hydrogens, and the halide adds to the carbon with fewer hydrogens.

Question 8

Which type of addition occurs when both atoms of a reagent are added to the same side of an alkene plane?

Accepted Answer

Syn addition

Question 9

What is the hybridization and bond angle of the carbon atoms in acetylene ($$\mathrm{C}_2\mathrm{H}_2$$)?

Accepted Answer

sp hybridized, 180°

Question 10

Which statement best describes the difference between terminal and internal alkynes?

Accepted Answer

Terminal alkynes have the triple bond at the end of the carbon chain, while internal alkynes have it between two carbon atoms within the chain.

Question 11

Which of the following bases is strong enough to deprotonate a terminal alkyne to form an acetylide anion?

Accepted Answer

$$\mathrm{NaNH}_2$$

Question 12

What is the product when 1 equivalent of $$\mathrm{Br}_2 is $$added to 1-butyne?

Accepted Answer

A trans-1,2-dibromoalkene

Question 13

Which reaction sequence converts an alkyne to a ketone via hydration?

Accepted Answer

Addition of $$\mathrm{H}_2\mathrm{O} in $$the presence of $$\mathrm{HgSO}_4$$ and $$\mathrm{H}_2\mathrm{SO}_4$$

Question 14

Which statement about tautomerization is correct?

Accepted Answer

Tautomerization is the interconversion between an enol and a keto form, often catalyzed by acid or base.

Question 15

Which of the following best describes the role of acetylide anions in organic synthesis?

Accepted Answer

They are good nucleophiles that attack electrophiles to form new carbon-carbon bonds.

Question 16

Which product is formed when 2 equivalents of $$\mathrm{HX}$$ are added to a terminal alkyne?

Accepted Answer

A geminal dihalide

Question 17

Which of the following reactions is an example of anti addition?

Accepted Answer

Halogenation of an alkene with $$\mathrm{Br}_2$$

Question 18

Which statement is true regarding the molecular orbital picture of ethylene ($$\mathrm{C}_2\mathrm{H}_4$$)?

Accepted Answer

The $$	ext{sp}^2$$ hybrid orbitals form the $$	ext{σ}$$ bonds, while the unhybridized $$2p_z$$ orbitals form the $$	ext{π}$$ bond.

Question 19

Which of the following is a correct application of the Index of Hydrogen Deficiency (IHD) formula for $$\mathrm{C}_4\mathrm{H}_6$$?

Accepted Answer

IHD = (4 - 6/2) + 1 = 2

Alkenes and Alkynes: Structure, Reactions, and Stereochemistry

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