Question 1

Which of the following statements best describes the difference between alkanes and alkenes?

Accepted Answer

Alkanes contain only single bonds between carbon atoms, while alkenes contain at least one double bond between carbon atoms.

Question 2

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

$$\mathrm{CH_3CH_2CH(CH_3$)CH_2CH_3}$$

Accepted Answer

2-methylpentane

Question 3

Which of the following best explains why branched alkanes have lower boiling points than their straight-chain isomers?

Accepted Answer

Branched alkanes have less surface area for dispersion forces, resulting in weaker intermolecular attractions.

Question 4

Which of the following is a constitutional isomer of hexane ($$\mathrm{C_6H_{14}}$$)?

Accepted Answer

2,2-dimethylbutane

Question 5

What is the hybridization of the nitrogen atom in the resonance structure (a) of acetamide shown below?

$$\mathrm{CH_3CONH_2} ($$with a lone pair on N and a double bond between C and O)

Accepted Answer

$$sp^2$$

Question 6

Which of the following best describes the most stable conformation of butane as seen in a Newman projection?

Accepted Answer

Staggered conformation with the two methyl groups anti to each other (180° apart)

Question 7

Which of the following cycloalkanes has the greatest ring strain?

Accepted Answer

Cyclopropane

Question 8

In the chair conformation of methylcyclohexane, which position is more stable for the methyl group?

Accepted Answer

Equatorial

Question 9

Which of the following is the correct molecular formula for cyclopentane?

Accepted Answer

$$\mathrm{C_5H_{10}}$$

Question 10

Which of the following statements about cis/trans isomerism in cycloalkanes is correct?

Accepted Answer

Cis/trans isomerism arises when two substituents are on the same or opposite sides of the ring.

Question 11

Which intermolecular force is primarily responsible for the higher boiling point of larger alkanes compared to smaller alkanes?

Accepted Answer

London dispersion forces

Question 12

What is the IUPAC name for the following compound?

$$\mathrm{(CH_3$)_2CHCH_2CH_3}$$

Accepted Answer

2-methylbutane

Question 13

Which of the following best describes a primary carbon?

Accepted Answer

A carbon atom bonded to only one other carbon atom

Question 14

Which of the following is the correct condensed structural formula for 2,4-dimethylhexane?

Accepted Answer

$$\mathrm{CH_3CH(CH_3$)CH_2CH(CH_3$)CH_2CH_3}$$

Question 15

Which of the following is NOT a rule for IUPAC naming of alkanes?

Accepted Answer

Always list sec- and tert- before iso- and neo- when alphabetizing

Question 16

Which of the following best explains why cyclohexane adopts a chair conformation?

Accepted Answer

To minimize both angle strain and torsional strain, achieving bond angles close to $$109.5^\circ$$

Question 17

Which of the following is a correct statement about the molecular formula of alkanes and cycloalkanes?

Accepted Answer

Cycloalkanes have two fewer hydrogens than their corresponding alkanes: $$C_nH_{2n} vs$$. $$C_nH_{2n+2}$$

Question 18

Which of the following is the best description of a gauche interaction in butane?

Accepted Answer

A staggered conformation where two methyl groups are $$60^\circ$$ apart

Question 19

Which of the following is the correct classification for the carbon bearing the positive charge in the carbocation below?

$$\mathrm{CH_3CH_2^+}$$

Accepted Answer

Primary carbocation

Hybridization and Resonance in Organic Molecules

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