Question 1

Which of the following statements best describes a constitutional isomer?

Accepted Answer

Compounds with the same molecular formula but different connectivity of atoms.

Question 2

What is the molecular formula for hexane?

Accepted Answer

$$\mathrm{C}_6\mathrm{H}_{14}$$

Question 3

Which of the following is the correct IUPAC name for the compound shown below?
A six-carbon chain with a methyl group attached to carbon 2.

Accepted Answer

2-methylhexane

Question 4

Which type of strain is associated with eclipsing interactions in Newman projections?

Accepted Answer

Torsional strain

Question 5

In the Newman projection of butane, what is the dihedral angle between the two methyl groups in the anti conformation?

Accepted Answer

$$180^\circ$$

Question 6

Which of the following is NOT a rule for selecting the parent chain in IUPAC nomenclature?

Accepted Answer

Select the chain with the most substituents regardless of length.

Question 7

What is the correct name for a cycloalkane with a five-membered ring and a two-carbon substituent attached to carbon 1?

Accepted Answer

Ethylcyclopentane

Question 8

Which of the following best describes a conformational isomer?

Accepted Answer

Isomers with identical connectivity but different 3D positions due to rotation about a single bond.

Question 9

What is the correct IUPAC name for the following compound?
A seven-carbon chain with ethyl groups attached to carbons 2 and 5.

Accepted Answer

2,5-diethylheptane

Question 10

Which of the following statements about cycloalkanes is TRUE?

Accepted Answer

Cycloalkanes are saturated cyclic hydrocarbons.

Question 11

What is the strain energy (in kcal/mol) associated with an eclipsed C–H bond in ethane?

Accepted Answer

$$1 	ext{ kcal/mol}$$

Question 12

Which of the following substituents is NOT considered when alphabetizing substituents in IUPAC nomenclature?

Accepted Answer

sec-butyl

Question 13

A molecule of 3-ethyl-2,2,6-trimethyloctane contains how many carbon atoms in its parent chain?

Accepted Answer

8

Question 14

Which of the following is a correct example of a branched alkyl group?

Accepted Answer

Isopropyl

Question 15

What is the correct condensed structural formula for 2-methylbutane?

Accepted Answer

$$\mathrm{CH}_3\mathrm{CH}(\,\mathrm{CH}_3)\mathrm{CH}_2\mathrm{CH}_3$$

Question 16

Which of the following best describes the difference between staggered and eclipsed conformations?

Accepted Answer

Staggered conformations have lower potential energy due to minimized torsional strain.

Question 17

Which of the following is the correct order of steps for naming a hydrocarbon according to IUPAC rules?

Accepted Answer

Identify parent chain, number chain, identify substituents, write name as a single word.

Question 18

Which of the following statements about octane rating is TRUE?

Accepted Answer

A higher octane rating means the fuel is less prone to autoignition.

Question 19

Which of the following is the correct IUPAC name for a compound with a six-membered ring and a three-carbon substituent attached to carbon 1?

Accepted Answer

Propylcyclohexane

Alkanes, Isomerism, and Nomenclature: Structure and Naming in Organic Chemistry

Study Guide - Practice Questions