what is characteristic of a radical chain termination step

Characteristic of a radical chain termination step

Which of the following statements is not true?
1.) homolytic cleavage of a bond in a neutral molecule
gives two radicals
2.) radicals have one or more unpaired electrons
3.) movement of single electrons is depicted using a
"fishhook arrow"
4.) the C-F bond is the weakest bond between carbon
atom and a halogen

 

·         4

 

Which of the following bonds has the lowest bond dissociation enthalpy?
1.) C-H
2.) C-F
3.) C-Br
4.) C-I

 

·         4

 

Which of the following bonds has the lowest bond dissociation enthalpy?

 

·         Trigonal planar

 

What is the bond angle of any alkyne?

 

·         180

 

Which of the following has the lowest pKa?
1.) Butane
2.) 1- Butene
3.) 1-Butyne
4.) 2-Butyne

 

·         3

 

Which of the following statements is not true?
1.)Bromine radicals add to the least substituted end of a
carbon-carbon double bond of an alkene
2.) The major anti-Markovnikov product obtained upon
addition of HBr to alkenes in the presence of a peroxide
is formed in a radical termination step.
3.)Two radicals combine in radical termination steps.
4.)Alkoxy radicals remove a hydrogen atom from HBr to
give an alcohol and a bromine atom.

 

·         2

 

What is the characteristic of a radical chain initiation step?

1.) radicals are formed
2.) substitution products are formed
3.) a radical reacts with a molecule to give a new radical
and a new molecule
4.) two radicals combine to give a molecule

 

·         1

 

What type of reactive intermediate is formed upon irradiation of a solution of toluene (Ph-CH3) and bromine?
1.) benzylic carbocation
2.) benzylic carbanion
3.) benzylic radical
4.) cyclic bromonium ion

 

·         3

 

What type of reactive intermediate is formed in the reaction of propene with hydrogen bromide in the presence of peroxides to give 1-bromopropane?
1.) 1° radical
2.) 1° carbocation
3.) 1° radical
4.) 2° radical

 

·         4

 

Which of the following anions in most nucleophilic in aprotic polar solvents?
1.)F
2.)Cl
3.)Br
4.)I

 

·         1

 

How many electrons does the allyl radical have in p orbitals?
1.)1
2.)2
3.)3
4.)4

 

·         3

 

which of the following is not a characteristic of sn1 reactions?
1.) The electrophilic carbon undergoes inversion of stereochemistry
2.)the rate is proportionate to the concentration of substrate
3.)the reaction proceeds faster in a more polar solvent
4.)the rate is independent of the concentration of the nuclephile

 

·         1

 

what is characteristic of a radical chain termination step?
1.)two radicals combine to give a molecule
2.)substitution products are formed
3.)radicals are formed
4.)a radical reacts with a molecule to give a new radical and a new molecule

 

·         1

 

what is characteristic of a radical propagation step?
1.)radicals are formed
2.) two radicals combine to give a molecule
3.) byproducts are formed
4.) a radical reacts with a molecule to give a new radical
and a new molecule

 

·         4

what is characteristic of a radical chain termination step?
1.)two radicals combine to give a molecule
2.)substitution products are formed
3.)radicals are formed
4.)a radical reacts with a molecule to give a new radical and a new molecule

 

·         1

 

Which of the following alkyl halides undergoes the fastest solvolysis reaction with methanol, CH3OH?
1.) methyl chloride
2.) ethyl chloride
3.) 2-chloropropane
4.) tert-butyl chloride

 

·         4

 

Which of the following has the list of compounds in the correct order of decreasing boiling point
(higher boiling point > lower boiling point)?
1.) 2-chloro-2-methylpropane > 2-chloropropane > chloroethane > chloromethane
2.) chloromethane > chloroethane > 2-chloropropane > 2-chloro-2-methylpropane
3.) chloroethane > chloromethane > 2-chloro-2-methylpropane > 2-chloropropane
4.) chloromethane > 2-chloro-2-methylpropane > 2-chloropropane > chloroethane

 

·         1