Question 1

Which of the following is the correct Lewis structure for the free radical CH\_3 (methyl radical)?

Accepted Answer

A carbon atom with three single bonds to hydrogen atoms and one unpaired electron on carbon.

Question 2

Given the molecular formula C\_4H\_6, which of the following structures represents a molecule with one triple bond?

Accepted Answer

A structure with two carbon atoms connected by a triple bond and each terminal carbon bonded to two hydrogens.

Question 3

What is the index of hydrogen deficiency (IHD) for a compound with the formula C\_{12}H\_8O\_2BrF?

Accepted Answer

$$IHD = 4$$

Question 4

Which of the following best describes the formal charge on the oxygen atom in the ion (CH\_3)\_2C=OH\^+?

Accepted Answer

The oxygen atom has a formal charge of $$+1.$$

Question 5

Which of the following skeletal structures corresponds to the condensed formula CH\_3CH\_2CH\_2COOH?

Accepted Answer

A four-carbon chain with a carboxylic acid group at the end.

Question 6

A molecule has the formula C\_7H\_5BrIN. How many elements of unsaturation does it have?

Accepted Answer

$$6$$

Question 7

Which of the following is a correct resonance structure for the acetate ion (CH\_3COO\^-)?

Accepted Answer

The negative charge is delocalized between the two oxygen atoms.

Question 8

Which of the following is NOT a constitutional isomer of an alkane with the molecular formula C\_8H\_{18}?

Accepted Answer

A structure with a double bond.

Question 9

For the molecule C\_4H\_8, which of the following structures does NOT show cis/trans isomerism but contains a carbon-carbon double bond?

Accepted Answer

1-butene

Question 10

Which of the following best describes the pushable electron pairs and resonance structure for the molecule below (with two adjacent oxygen atoms, each with lone pairs, attached to a carbon chain)?

Accepted Answer

Lone pairs on oxygen can be pushed to form a double bond with carbon, resulting in a resonance structure with a negative charge on the other oxygen.

Question 11

Which of the following is the correct condensed structure for a molecule with the model: black = C, white = H, red = O, green = Cl, and the structure shows a three-carbon chain with a chlorine on the first carbon?

Accepted Answer

CH\_3CH\_2CH\_2Cl

Question 12

How many acyclic isomers (including stereoisomers) exist for the formula C\_3H\_5Cl?

Accepted Answer

4

Question 13

Which of the following best describes the resonance contributors for the species CH\_3CONH\_2 (acetamide) and their relative stabilities?

Accepted Answer

The resonance form with a double bond between C and O and a neutral NH\_2 is more stable than the form with a double bond between C and N and a positive charge on N.

Question 14

Given the molecular formula C\_6H\_5NO\_2, how many elements of unsaturation are present?

Accepted Answer

$$5$$

Question 15

Which of the following is the correct skeletal structure for (CH\_3)\_3COC(CH\_3)\_3?

Accepted Answer

A central oxygen atom bonded to two tert-butyl groups.

Question 16

Which of the following best describes the process for determining the index of hydrogen deficiency (IHD) for a compound with the formula C\_nH\_mX\_yN\_z?

Accepted Answer

Use the formula $$IHD = \frac{2n + 2 + z - m - y}{2}$$, where n = number of carbons, m = number of hydrogens, y = number of halogens, z = number of nitrogens.

Question 17

Which of the following is a correct application of formal charge calculation for the nitrogen atom in H\_3CNH\_3\^+?

Accepted Answer

The nitrogen atom has a formal charge of $$+1$$ because it has four bonds and no lone pairs.

Question 18

Which of the following condensed formulas corresponds to a molecule with two tert-butyl groups connected by an oxygen atom?

Accepted Answer

(CH\_3)\_3COC(CH\_3)\_3

Question 19

Which of the following best describes the relationship between resonance and stability in carboxylate ions?

Accepted Answer

Resonance delocalizes the negative charge over two oxygen atoms, increasing stability.

Organic Chemistry Fundamentals: Lewis Structures, Isomerism, and Unsaturation

Study Guide - Practice Questions

Study Guide - Flashcards