Question 1

Which of the following statements best explains why the central C–C bond in buta-1,3-diene is shorter than a typical C–C single bond?

Accepted Answer

The central bond is strengthened by the overlap of adjacent p orbitals, resulting in partial double bond character due to conjugation.

Question 2

What is the hybridization of each carbon atom in buta-1,3-diene?

Accepted Answer

sp2

Question 3

Which of the following best describes the electron density in the π bonds of a conjugated diene such as buta-1,3-diene?

Accepted Answer

The electron density is delocalized over all four carbons.

Question 4

Which of the following is a key requirement for resonance to occur in a molecule?

Accepted Answer

There must be overlapping p orbitals on three or more adjacent atoms.

Question 5

Why are allylic carbocations unusually stable compared to typical primary carbocations?

Accepted Answer

They are stabilized by resonance delocalization of the positive charge over multiple atoms.

Question 6

Which of the following is the correct resonance structure for the allyl carbocation?

Accepted Answer

$\ce{CH2=CH-CH2^+} \leftrightarrow \ce{CH2^+-CH=CH2}$

Question 7

Which of the following factors does NOT contribute to a resonance structure being a major contributor to the resonance hybrid?

Accepted Answer

The structure has more atoms with incomplete octets.

Question 8

Which of the following best describes the hybridization and geometry of the carbocation center in an allylic carbocation?

Accepted Answer

sp2 hybridized, trigonal planar

Question 9

Which of the following is true regarding the resonance hybrid of the allyl carbocation?

Accepted Answer

The positive charge is delocalized over two carbon atoms.

Question 10

Which of the following molecules would NOT exhibit resonance?

Accepted Answer

A molecule with only single bonds and no lone pairs.

Question 11

Which of the following best explains why the resonance hybrid is more stable than any individual resonance structure?

Accepted Answer

The resonance hybrid allows for delocalization of electrons, lowering the overall energy.

Question 12

Which of the following is the correct order of carbocation stability, from least to most stable?

Accepted Answer

Methyl < 1° < allyl ≈ 2° < 3°

Question 13

Which of the following best describes the bonding in benzene?

Accepted Answer

Six delocalized π electrons over six carbon atoms.

Question 14

Which of the following is a necessary condition for a molecule to be considered conjugated?

Accepted Answer

It must have alternating single and double bonds.

Question 15

Which of the following best explains why the acetate ion ($\ce{CH3COO^-}$) is stabilized by resonance?

Accepted Answer

The negative charge is delocalized over two oxygen atoms.

Question 16

Which of the following is NOT a valid resonance move?

Accepted Answer

Moving a σ bond to an adjacent atom.

Question 17

Which of the following best describes the effect of conjugation on the reactivity of 1,3-dienes in Diels-Alder reactions?

Accepted Answer

Conjugation increases the reactivity by delocalizing electrons, making the diene more reactive.

Question 18

Which of the following best explains why negative charge is more stable on an oxygen atom than on a carbon atom in resonance structures?

Accepted Answer

Oxygen is more electronegative than carbon.

Question 19

Which of the following is a real-life application of resonance stabilization?

Accepted Answer

The color of organic dyes, such as those used in food and textiles, is often due to extended conjugation and resonance stabilization.

Ch. 16 Part 1

Study Guide - Practice Questions