Question 1

Which of the following best describes the mechanism of free radical substitution in alkanes?

Accepted Answer

It consists of initiation, propagation, and termination steps involving free radicals.

Question 2

During the free radical chlorination of methane, what is the role of high intensity light?

Accepted Answer

It initiates the formation of chlorine radicals by homolytic cleavage of $$Cl_2.$$

Question 3

Which product is formed when excess $$Cl_2 is $$used in the chlorination of methane?

Accepted Answer

Tetrachloromethane ($$CCl_4)$$

Question 4

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

Accepted Answer

Alkenes are electron-rich due to their pi bonds, making them susceptible to electrophilic attack.

Question 5

According to Markovnikov's rule, in the addition of $$HBr to $$propene, where does the bromine atom attach?

Accepted Answer

To the carbon atom with the fewer number of hydrogen atoms.

Question 6

Which condition leads to anti-Markovnikov addition in the reaction of $$HBr$$ with alkenes?

Accepted Answer

Presence of peroxides.

Question 7

What is the major product when 1-heptyne reacts with excess $$HBr$$?

Accepted Answer

1,1-Dibromoheptane

Question 8

Which of the following best describes the stability order of carbocations?

Accepted Answer

Tertiary \u003e Secondary \u003e Primary

Question 9

Which compound reacts rapidly with bromine ($$Br_2) at $$room temperature in the dark?

Accepted Answer

Isobutene

Question 10

What is the stereochemistry of the product formed during the halogenation (bromination) of cyclohexene?

Accepted Answer

Anti addition

Question 11

Which catalyst is commonly used for the hydrogenation of alkenes?

Accepted Answer

Palladium on carbon ($$Pd/C)$$

Question 12

In the hydration of a terminal alkyne, which catalyst is required to form a ketone?

Accepted Answer

Mercuric ion ($$Hg^{2+})$$

Question 13

Which of the following is a correct description of the propagation step in free radical substitution?

Accepted Answer

Radicals react with stable molecules to form new radicals and products.

Question 14

What is the product of the hydration of an internal alkyne in the presence of sulfuric acid?

Accepted Answer

Ketone

Question 15

Which of the following best explains the regioselectivity observed in Markovnikov addition?

Accepted Answer

The formation of the more stable carbocation intermediate.

Question 16

Which reaction type involves the conversion of a pi bond to two sigma bonds?

Accepted Answer

Addition reaction

Question 17

During the rearrangement of carbocations, what is the purpose of a 1,2-hydride shift?

Accepted Answer

To move the positive charge to a more stable carbocation center.

Question 18

Which of the following is true about the addition of water to a terminal alkyne?

Accepted Answer

It requires a mercuric ion catalyst and forms a ketone after tautomerization.

Question 19

Which of the following is a test for the presence of alkenes using bromine?

Accepted Answer

Red/brown color of bromine disappears when alkene is present.

Question 20

Which of the following reactions is an example of syn addition?

Accepted Answer

Hydrogenation of alkenes

Hydrocarbons II: Substitution and Addition Reactions of Alkanes, Alkenes, and Alkynes

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