Question 1

Which statement best explains why alkenes are more reactive than alkanes?

Accepted Answer

Alkenes contain a carbon-carbon double bond, which is a region of high electron density and can participate in addition reactions.

Question 2

What is the molecular geometry around each carbon atom in ethylene ($$C_2H_4$$)?

Accepted Answer

Trigonal planar

Question 3

Which of the following best describes the hybridization of the carbon atoms in ethylene ($$C_2H_4$$)?

Accepted Answer

sp\^2

Question 4

Why is the C—C bond length shorter in ethylene than in ethane?

Accepted Answer

The pi bond in ethylene brings the carbon atoms closer together, shortening the bond length.

Question 5

Which of the following formulas has two degrees of unsaturation?

Accepted Answer

$$C_5H_8$$

Question 6

A compound has the formula $$C_4H_7Br. $$How many degrees of unsaturation does it have?

Accepted Answer

1

Question 7

Which element should be ignored when calculating degrees of unsaturation in a molecular formula?

Accepted Answer

Oxygen

Question 8

What is the correct IUPAC name for a five-carbon chain with a double bond between carbons 2 and 3?

Accepted Answer

pent-2-ene

Question 9

Which statement about cis-trans isomerism in alkenes is correct?

Accepted Answer

Cis-trans isomerism occurs when each carbon of the double bond has two different substituents.

Question 10

According to E-Z nomenclature, what is the configuration of an alkene if the highest priority groups are on opposite sides of the double bond?

Accepted Answer

E

Question 11

Which of the following statements about cycloalkenes is true?

Accepted Answer

All cycloalkenes are assumed to be cis unless specifically named trans.

Question 12

Which rule states that a bridged bicyclic compound cannot have a double bond at a bridgehead position unless one of the rings contains at least eight carbon atoms?

Accepted Answer

Bredt's Rule

Question 13

Which product is favored in an E2 elimination using a bulky base?

Accepted Answer

The Hofmann product (least substituted alkene)

Question 14

Which of the following best describes the stereochemistry required for an E2 elimination to occur?

Accepted Answer

The leaving group and the hydrogen must be anti-coplanar.

Question 15

Which of the following conditions favors elimination over substitution in alkyl halides?

Accepted Answer

High temperature and bulky base

Question 16

Which statement about the heat of hydrogenation of alkenes is correct?

Accepted Answer

The more substituted the double bond, the lower its heat of hydrogenation.

Question 17

A student is given the formula $$C_6H_7N. $$How many degrees of unsaturation does this compound have?

Accepted Answer

4

Question 18

Which of the following is a correct application of Zaitsev's Rule?

Accepted Answer

The most substituted alkene is the major product.

Question 19

Which physical property is generally higher in cis alkenes compared to trans alkenes?

Accepted Answer

Boiling point

Question 20

Which of the following is a commercial use of ethylene?

Accepted Answer

Production of polyethylene

Structure and Synthesis of Alkenes – Comprehensive Study Notes

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