Question 1

Which of the following Newman projections represents the lowest energy conformation of n-butane when viewed down the C2–C3 bond axis?

Accepted Answer

A staggered conformation with the two methyl groups anti to each other ($$180^\circ$$ apart)

Question 2

Given the following reaction: $$\mathrm{(CH_3$)_3C-H + Br_2$ \xrightarrow{hv} (CH_3$)_3C-Br + HBr}$$, what is the first step in the radical mechanism?

Accepted Answer

Homolytic cleavage of $$Br_2 to $$form two $$Br^\cdot$$ radicals

Question 3

Which of the following compounds is expected to have the greatest water solubility?

Accepted Answer

$$NH_2CH_3$$

Question 4

Assign the correct hybridization to the positively charged carbon in the benzyl carbocation ($$C_6H_5CH_2^+).$$

Accepted Answer

$$sp^3$$

Question 5

Which of the following statements best explains why the anti conformation of n-butane is lower in energy than the gauche conformation?

Accepted Answer

Steric repulsion between the two methyl groups is minimized in the anti conformation

Question 6

Which of the following molecules contains a chiral center?

Accepted Answer

$$CH_3CH(OH)CO_2H$$

Question 7

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

[Structure: a heptane chain with ethyl and two methyl groups at position 4]

Accepted Answer

3-ethyl-4,4-dimethylheptane

Question 8

Which of the following pairs of molecules are enantiomers?

Accepted Answer

Two molecules with opposite configurations at all chiral centers

Question 9

Which functional group is present in the following molecule: $$CH_3CH_2OH$$?

Accepted Answer

Alcohol

Question 10

Which of the following acids is the strongest according to the provided $$pK_a$$ values?

Accepted Answer

$$HCl$$

Question 11

What is the relationship between the following two molecules: (1) $$BrCH_2CH(OH)CO_2H$$ and (2) $$BrCH_2CH(OH)CO_2H$$ with opposite configuration at the chiral center?

Accepted Answer

Enantiomers

Question 12

Which of the following statements about meso compounds is correct?

Accepted Answer

Meso compounds are achiral despite having chiral centers

Question 13

Which of the following elements has the highest electronegativity according to the Pauling scale?

Accepted Answer

Fluorine ($$F)$$

Question 14

Which of the following is the correct Fischer projection for $$D-$$glyceraldehyde?

Accepted Answer

A projection with the $$OH$$ group on the right at the chiral center

Question 15

Which of the following is the correct order of acid strength from strongest to weakest?

Accepted Answer

$$HCl \u003e CH_3CO_2H \u003e H_2O \u003e NH_3$

Question 16

Which of the following is a plausible product of the reaction between $$CH_3CO_2H$$ and $$HCN$$?

Accepted Answer

$$CH_3CO_2H + CN^-$$

Question 17

Which of the following is the correct hybridization for the central carbon in $$CO_2$$?

Accepted Answer

$$sp$$

Question 18

Which of the following best describes the stereoisomeric relationship between the two molecules shown below?

[Structure: two molecules with two chiral centers, one matching and one opposite]

Accepted Answer

Diastereomers

Question 19

Which of the following is the correct mechanism for the propagation step in the radical bromination of tert-butane?

Accepted Answer

$$Br^\cdot + (CH_3$)_3C-H \rightarrow (CH_3$)_3C^\cdot + HBr$$

Question 20

Which of the following is the correct electron configuration for a neutral nitrogen atom?

Accepted Answer

$$1s^2$$\ $$2s^2$$\ $$2p^3$$

Organic Chemistry Study Guide: Conformations, Mechanisms, Stereochemistry, and Acid-Base Properties

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