Question 1

Which of the following best describes the general formula for cycloalkanes?

Accepted Answer

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

Question 2

Which of the following statements about the physical properties of alkanes and cycloalkanes is CORRECT?

Accepted Answer

They are insoluble in water and float due to lower density.

Question 3

Which of the following is a correct representation of a radical substitution reaction involving methane and chlorine?

Accepted Answer

$$\mathrm{CH}_4 + \mathrm{Cl}_2 \xrightarrow{\Delta/\mathrm{hv}} \mathrm{CH}_3\mathrm{Cl} + \mathrm{HCl}$$

Question 4

Which of the following best explains why tertiary carbons are more stable than primary carbons in carbocation intermediates?

Accepted Answer

Tertiary carbons are stabilized by three alkyl groups through hyperconjugation and induction.

Question 5

Which of the following is the correct order of reactivity for alkyl radical formation by chlorine at room temperature?

Accepted Answer

3° \u003e 2° \u003e 1°

Question 6

A reaction energy diagram shows a single peak and a negative $$\Delta G^\circ. $$Which of the following best describes this reaction?

Accepted Answer

Fast, exergonic

Question 7

Which of the following is a product of the complete combustion of ethane ($$\mathrm{C}_2\mathrm{H}_6$$)?

Accepted Answer

$$\mathrm{CO}_2$$

Question 8

Which of the following best describes the initiation step in the radical halogenation of alkanes?

Accepted Answer

A halogen molecule undergoes homolytic cleavage to form two halogen radicals.

Question 9

In the radical halogenation of 2-methylpentane with bromine, which product is most likely to be formed?

Accepted Answer

3° alkyl bromide

Question 10

Which of the following statements about the reactivity-selectivity principle is correct?

Accepted Answer

The more reactive a species, the less selective it is.

Question 11

Which of the following best describes the propagation step in the radical halogenation of methane?

Accepted Answer

A halogen radical abstracts a hydrogen atom from methane, forming a methyl radical and hydrogen halide.

Question 12

Which of the following is NOT a type of general organic reaction mechanism?

Accepted Answer

Ionic mechanism

Question 13

Which of the following is the correct formula for a branched-chain alkane with five carbons?

Accepted Answer

$$\mathrm{C}_5\mathrm{H}_{12}$$

Question 14

Which of the following best explains why excess alkane is used in halogenation reactions to maximize monohalogenation?

Accepted Answer

To prevent the formation of polyhalogenated products.

Question 15

Which of the following is a correct statement about the boiling points of alkanes and cycloalkanes?

Accepted Answer

Boiling points increase as the carbon chain increases due to more London dispersion forces.

Question 16

Which of the following is the correct classification for the reaction: $$\mathrm{AB} + \mathrm{X} \rightarrow \mathrm{AX} + \mathrm{B}$$?

Accepted Answer

Single displacement (substitution)

Question 17

Which of the following best describes the termination step in a radical substitution reaction?

Accepted Answer

Two radicals combine to form a stable molecule, reducing the number of radicals.

Question 18

Which of the following is a correct statement about the products of cracking?

Accepted Answer

Cracking produces smaller alkanes and alkenes.

Question 19

Which of the following is the correct formula for a cycloalkane with six carbons?

Accepted Answer

$$\mathrm{C}_6\mathrm{H}_{12}$$

Question 20

Which of the following best describes an exergonic reaction?

Accepted Answer

A reaction that releases energy and has a negative $$\Delta G^\circ$$

Alkanes and Cycloalkanes: Properties, Reactions, and Mechanisms

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