Question 1

Which of the following is the correct Lewis structure for carbon dioxide ($$\mathrm{CO_2$}$$), and what is the formal charge on each oxygen atom?

Accepted Answer

Each oxygen has a formal charge of $$0$$; the structure is $$\mathrm{O=C=O}$$ with double bonds.

Question 2

Which of the following statements about resonance structures is TRUE?

Accepted Answer

Resonance structures must have the same number of valence electrons.

Question 3

Given the molecule $$\mathrm{CH_2$=CH_2$} ($$ethylene), what is the hybridization of each carbon atom and the approximate bond angle?

Accepted Answer

$$sp^2$$ hybridized, $$120^\circ$$

Question 4

Which of the following best describes the difference between a Bronsted-Lowry acid and a Lewis acid?

Accepted Answer

A Bronsted-Lowry acid donates a proton; a Lewis acid accepts an electron pair.

Question 5

Which of the following molecules is chiral?

Accepted Answer

2-butanol ($$\mathrm{CH_3CH(OH)CH_2CH_3})$$

Question 6

Which of the following is the correct IUPAC name for the compound with the structure $$\mathrm{(CH_3$)_2CHCH_2CH_3}$$?

Accepted Answer

2-methylbutane

Question 7

Which conformation of butane has the lowest potential energy?

Accepted Answer

Staggered anti conformation with methyl groups $$180^\circ$$ apart

Question 8

In the free-radical chlorination of methane, which step is the rate-determining step?

Accepted Answer

First propagation step (hydrogen abstraction)

Question 9

Which of the following carbocations is the most stable?

Accepted Answer

Tertiary carbocation ($$\mathrm{(CH_3$)_3C^+})$$

Question 10

Which of the following statements about SN2 reactions is CORRECT?

Accepted Answer

The reaction proceeds with inversion of configuration at the stereocenter.

Question 11

Which of the following is the correct order of increasing reactivity toward SN1 reactions?

Accepted Answer

Methyl \u003c Primary \u003c Secondary \u003c Tertiary

Question 12

How many degrees of unsaturation (index of hydrogen deficiency, IHD) are present in $$\mathrm{C_6H_{10}}$$?

Accepted Answer

2

Question 13

Which of the following is the correct E/Z designation for the alkene $$\mathrm{CH_3CH=$$CHCH_3$$}$$?

Accepted Answer

E-2-butene

Question 14

Which of the following statements about the E2 elimination mechanism is TRUE?

Accepted Answer

It requires a strong base and a good leaving group.

Question 15

Which of the following is a meso compound?

Accepted Answer

2,3-dibromobutane (with both Br on the same side)

Question 16

What is the maximum number of stereoisomers possible for a molecule with three chiral centers?

Accepted Answer

8

Question 17

Which of the following best describes the product of the dehydration of 2-butanol under acidic conditions?

Accepted Answer

2-butene (major) and 1-butene (minor)

Question 18

Which of the following is the correct IUPAC name for the compound $$\mathrm{CH_3C\equiv CCH_2CH_3}$$?

Accepted Answer

2-pentyne

Question 19

Which of the following statements about the Hammond Postulate is CORRECT?

Accepted Answer

The transition state of an exothermic reaction resembles the reactants.

Question 20

Which of the following is the correct relationship between the following two compounds: (R)-2-butanol and (S)-2-butanol?

Accepted Answer

They are enantiomers.

Organic Chemistry I: Core Concepts and Mechanisms (Chapters 1–9)

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