Question 1

Which of the following statements best explains why alkanes are considered 'saturated' hydrocarbons?

Accepted Answer

They contain only single bonds between carbon atoms, allowing the maximum number of hydrogen atoms to bond to each carbon.

Question 2

Which intermolecular force is primarily responsible for the physical properties of alkanes?

Accepted Answer

London dispersion forces

Question 3

What is the general molecular formula for a cycloalkane with $$n$$ carbon atoms?

Accepted Answer

$$C_nH_{2n}$$

Question 4

Which of the following best describes the difference in boiling points between butane and isobutane?

Accepted Answer

Butane has a higher boiling point because its linear structure allows for more substantial dispersion interactions.

Question 5

Which of the following is the correct IUPAC name for the molecule with the structure $$CH_3CH_2CH(CH_3$)CH_2CH_3$$?

Accepted Answer

3-methylpentane

Question 6

When drawing a line-angle (skeletal) structure, what is assumed about the hydrogen atoms?

Accepted Answer

Hydrogen atoms are assumed to be present to give each carbon four bonds.

Question 7

Which of the following is a constitutional isomer of $$C_5H_{12}$$?

Accepted Answer

2,2-dimethylpropane

Question 8

What is the main reason that cyclopropane is much less stable than cyclohexane?

Accepted Answer

Cyclopropane has significant angular and torsional strain due to its 60° bond angles and eclipsed hydrogens.

Question 9

Which conformation of butane is the most stable?

Accepted Answer

Anti-staggered, where the two methyl groups are 180° apart.

Question 10

A cyclohexane ring is substituted with a single tert-butyl group. Which chair conformation is most stable?

Accepted Answer

The conformation where the tert-butyl group is equatorial.

Question 11

Which of the following best describes the difference between cis- and trans-1,3-dimethylcyclohexane?

Accepted Answer

In the cis isomer, both methyl groups are on the same side of the ring; in the trans isomer, they are on opposite sides.

Question 12

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

$$\mathrm{CH_3CH_2CH(CH_3$)CH_2CH_2CH_3}$$

Accepted Answer

3-methylhexane

Question 13

Which of the following statements about the water solubility of alkanes is correct?

Accepted Answer

Water solubility decreases as the length of the alkane increases.

Question 14

Which of the following is the correct condensed structural formula for 2,3-dimethylbutane?

Accepted Answer

$$CH_3CH(CH_3$)CH(CH_3$)CH_3$

Question 15

Which of the following best explains why dodecane ($$C_{12}H$$_{26}$$) has a much higher boiling point than methane (CH_4$)?

Accepted Answer

Dodecane has a much larger surface area, leading to stronger London dispersion forces.

Question 16

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

$$\mathrm{CH_3CH_2CH_2CH_2CH_3}$$

Accepted Answer

Pentane

Question 17

Which of the following is a correct statement about the conformational analysis of cyclohexane?

Accepted Answer

The chair conformation is the most stable due to minimal torsional and angular strain.

Question 18

Which of the following is the correct IUPAC name for a cycloalkane with two methyl groups on carbons 1 and 3, both pointing up (same side)?

Accepted Answer

cis-1,3-dimethylcyclohexane

Question 19

Which of the following best describes the effect of branching on the boiling point of alkanes?

Accepted Answer

Branching decreases the boiling point because it reduces the surface area for dispersion forces.

Alkanes and Cycloalkanes: Structure, Properties, and Nomenclature

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