Q: Which of the following bonds has the highest bond dissociation energy (BDE)? A. $\displaystyle \text{C-H}$ in methane B. $\displaystyle \text{C-H}$ in benzene C. $\displaystyle \text{C-H}$ in ethane D. $\displaystyle \text{C-H}$ in cyclohexane Select the correct answer.

A. $\displaystyle \text{C-H}$ in methane

Question 1

Which of the following compounds is the most acidic?

$\displaystyle 	ext{A. Benzoic acid (C}_6	ext{H}_5	ext{COOH)}$

$\displaystyle 	ext{B. Acetic acid (CH}_3	ext{COOH)}$

$\displaystyle 	ext{C. Trichloroacetic acid (CCl}_3	ext{COOH)}$

$\displaystyle 	ext{D. 3-Butenoic acid (CH}_2	ext{=CHCH}_2	ext{COOH)}$

Select the correct answer.

Accepted Answer

C. Trichloroacetic acid

Question 2

Which of the following cyclohexane chair conformers is the most stable?

A. All substituents are axial

B. All substituents are equatorial

C. One substituent is axial, others are equatorial

D. Two substituents are axial, one is equatorial

Select the correct answer.

Accepted Answer

B. All substituents are equatorial

Question 3

Which of the following anions is the most stable due to resonance?

A. Phenoxide ion ($\displaystyle 	ext{C}_6	ext{H}_5	ext{O}^-$)

B. Cyclohexanone enolate ($\displaystyle 	ext{C}_6	ext{H}_{10}	ext{O}^-$)

C. Acetate ion ($\displaystyle 	ext{CH}_3	ext{COO}^-$)

D. Cyclopentadienyl anion ($\displaystyle 	ext{C}_5	ext{H}_5^-$)

Select the correct answer.

Accepted Answer

D. Cyclopentadienyl anion

Question 4

Which of the following radicals is the most stable?

A. $\displaystyle (CH_3)_3C\cdot$

B. $\displaystyle (CH_3)_2CH\cdot$

C. $\displaystyle CH_2=CHCH_2\cdot$

D. $\displaystyle CH_3CH_2\cdot$

Select the correct answer.

Accepted Answer

A. $\displaystyle (CH_3)_3C\cdot$

Question 5

Which of the following compounds will yield the greatest number of unique monochlorinated products upon free radical chlorination?

A. Methylcyclohexane

B. 1,2-Dimethylcyclohexane

C. 1,3,5-Trimethylcyclohexane

D. Cyclohexane

Select the correct answer.

Accepted Answer

B. 1,2-Dimethylcyclohexane

Question 6

Which of the following bonds has the highest bond dissociation energy (BDE)?

A. $\displaystyle 	ext{C-H}$ in methane

B. $\displaystyle 	ext{C-H}$ in benzene

C. $\displaystyle 	ext{C-H}$ in ethane

D. $\displaystyle 	ext{C-H}$ in cyclohexane

Select the correct answer.

Accepted Answer

A. $\displaystyle 	ext{C-H}$ in methane

Question 7

Which of the following alkyl halides will react fastest in an $\displaystyle S_N2$ reaction?

A. 1-Bromopentane

B. 2-Bromo-2-methylbutane

C. 2-Bromopentane

D. tert-Butyl bromide

Select the correct answer.

Accepted Answer

A. 1-Bromopentane

Question 8

Which of the following alcohols is the most acidic?

A. Cyclohexanol

B. Phenol

C. tert-Butanol

D. Cyclopentanol

Select the correct answer.

Accepted Answer

B. Phenol

Question 9

Which of the following nucleophiles is the strongest in a polar aprotic solvent?

A. $\displaystyle CH_3O^-$

B. $\displaystyle CH_3NH_2$

C. $\displaystyle CH_3S^-$

D. $\displaystyle CH_3OH$

Select the correct answer.

Accepted Answer

C. $\displaystyle CH_3S^-$

Question 10

Which of the following alkenes is the most stable?

A. 1-Butene

B. trans-2-Butene

C. cis-2-Butene

D. 2,3-Dimethyl-2-butene

Select the correct answer.

Accepted Answer

D. 2,3-Dimethyl-2-butene

Question 11

Which of the following compounds will react fastest with $\displaystyle HBr$ in an addition reaction?

A. 1-Butene

B. 2-Butene

C. 2-Methylpropene

D. 1,3-Butadiene

Select the correct answer.

Accepted Answer

C. 2-Methylpropene

Question 12

Which of the following statements about resonance contributors is correct?

A. The resonance structure with the most covalent bonds is always the major contributor.

B. The resonance structure with the least formal charges and full octets is usually the major contributor.

C. The resonance structure with the most charges is always the major contributor.

D. The resonance structure with positive charges on the most electronegative atom is the major contributor.

Select the correct answer.

Accepted Answer

B. The resonance structure with the least formal charges and full octets is usually the major contributor.

Question 13

Which of the following reagents would convert 1-butyne to 2-butanone in the fewest steps?

A. $\displaystyle 1) BH_3, 2) H_2O_2, OH^-$

B. $\displaystyle 1) HgSO_4, H_2SO_4, H_2O$

C. $\displaystyle 1) O_3, 2) Zn, H_2O$

D. $\displaystyle 1) H_2, Lindlar's catalyst$

Select the correct answer.

Accepted Answer

B. $\displaystyle 1) HgSO_4, H_2SO_4, H_2O$

Question 14

Which of the following statements about $\displaystyle S_N2$ reactions is correct?

A. $\displaystyle S_N2$ reactions proceed faster with tertiary alkyl halides.

B. $\displaystyle S_N2$ reactions are stereospecific and result in inversion of configuration.

C. $\displaystyle S_N2$ reactions require a carbocation intermediate.

D. $\displaystyle S_N2$ reactions are favored by polar protic solvents.

Select the correct answer.

Accepted Answer

B. $\displaystyle S_N2$ reactions are stereospecific and result in inversion of configuration.

Question 15

Which of the following is the correct IUPAC name for the following structure?

A cyclohexane ring with a methyl group at C1 and an ethyl group at C3.

A. 1-Ethyl-3-methylcyclohexane

B. 3-Ethyl-1-methylcyclohexane

C. 1-Methyl-3-ethylcyclohexane

D. 3-Methyl-1-ethylcyclohexane

Select the correct answer.

Accepted Answer

C. 1-Methyl-3-ethylcyclohexane

Question 16

Which of the following statements best explains why phenol is more acidic than cyclohexanol?

A. Phenol has a lower molecular weight.

B. The phenoxide ion is stabilized by resonance with the aromatic ring.

C. Cyclohexanol is more soluble in water.

D. Phenol has more hydrogens.

Select the correct answer.

Accepted Answer

B. The phenoxide ion is stabilized by resonance with the aromatic ring.

Question 17

Which of the following is the correct hybridization and bond angle for the carbonyl carbon in acetone ($\displaystyle (CH_3)_2CO$)?

A. $\displaystyle sp^3$, $109.5^\circ$

B. $\displaystyle sp^2$, $120^\circ$

C. $\displaystyle sp$, $180^\circ$

D. $\displaystyle sp^2$, $109.5^\circ$

Select the correct answer.

Accepted Answer

B. $\displaystyle sp^2$, $120^\circ$

Question 18

Which of the following statements about the reactivity of alkyl halides in $\displaystyle S_N1$ reactions is correct?

A. Methyl halides react fastest.

B. Primary alkyl halides react faster than tertiary alkyl halides.

C. Tertiary alkyl halides react fastest due to carbocation stability.

D. Secondary alkyl halides never react via $\displaystyle S_N1$.

Select the correct answer.

Accepted Answer

C. Tertiary alkyl halides react fastest due to carbocation stability.

Question 19

Which of the following best describes the product of the reaction of 1-butyne with $\displaystyle 1) BH_3, 2) H_2O_2, OH^-$?

A. 2-Butanone

B. 1-Butanol

C. Butanal

D. 1-Butanone

Select the correct answer.

Accepted Answer

C. Butanal

Comprehensive Organic Chemistry Practice: Structure, Reactivity, and Mechanisms

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