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CHEM 333: Final Exam
Which of the following statements is not true regarding resonance structures?
a. Each atom in all of the resonance structures must have a complete shell of valence electrons
b. The resonance structures may have different energies
c. All resonance structures must have the same arrangement of atoms
d. All resonance structures must have the same number of electrons
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a. Each atom in all of the resonance structures must have a complete shell of valence electrons
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Which atomic orbitals overlap to form the carbon-carbon triple bond on an alkyne?
a. s+s; sp + sp; p + p
b. sp + sp; sp + sp; p + p
c. sp + sp; p + p; p + p
d. sp^2 + sp^2; sp + sp; p + p
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c. sp + sp; p + p; p + p
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Which of the following has the list of compounds in the correct order of decreasing polarity? (more polar > less polar)?
a. CCl4 > CHCL3 > CH2CL2
b. CH2CL2 > CHCL3 > CCL4
c. CCL4 > CH2CL2 > CHCL3
d. CHCL3 > CCL4 > CH2CL2
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b. CH2CL2 > CHCL3 > CCL4
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Which of the following molecules is not linear?
a. H2O
b. CO2
c. HC(triple bond)CH
d. Cl2
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a. H2O
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How many sigma bonds are there in ethane that are formed by sp-sp3 overlap?
a. 7
b. 6
c. 5
d. 3
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b. 6
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Which of the following statements is not true?
a. The sp3 C-H bond of an alkane is weaker than the sp C-H bond of an alkyne
b. The carbon-carbon triple bond of an alkyne is shorter than the carbon-carbon double bond of an alkene
c. The carbon-carbon triple bond of an alkene is shorter than the carbon-carbon double bond of an alkane
d. The sp3 C-H bond of an alkane is longer than the sp C-H bond of an alkyne
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c. The carbon-carbon triple bond of an alkene is shorter than the carbon-carbon double bond of an alkane
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Which of the following is not true regarding alkanes?
a. Alkenes are non polar
b. Alkenes burn in air to give H2O and CO2
c. Alkenes are highly miscible with water
d. The strongest intermolecular force between alkene molecules is the van der Waals interaction
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c. alkenes are highly miscible with water
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For a molecule to possess a dipole moment, which following conditions is necessary but not sufficient?
a. Three or more atoms in the molecule
b. Presence of one or more polar bonds
c. A non-linear structure
d. Absence of a carbon-carbon double or triple bond
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b. Presence of one or more polar bonds
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As a consequence of the leveling effect which of the following is present in the highest concentration upon dissolution of H2SO4 in water?
a. H3O+
b. H+
c. H2SO4
d. HO-
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a
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Which of the following is a true statement?
a. The strong the acid the larger it's pKa
b. Strong acids can have a negative pKa valye
c. Acid-Base reactions always favor the formation of the stronger acid
d. The conjugate base of a strong acid is a strong base
e. Hydrogen need not be in the molecular formula of a Bronsted Lowry Acid
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b
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Select the strongest base
a. HO-
b. RC(triplebond)C-
c. CH3CH2-
d. NH2-
e. CH2=CH-
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c
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Which of the following terms describes the role of HBR in this acid base reaction
H2C=CH2 + H-Br --> H3C-CH2 +Br-
a. Bronsted Lowry base
b. Lewis base
c. Bronsted Lowry acid and not a Lewis Acid
d. Bronsted Lowry acid and Lewis acid
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d
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What is the simplest alkane i.e. the one with the smallest molecular weight, which possesses primary, secondary, tertiary carbon atoms?
a. 2-methylpropane
b. 2-methylpentane
c. 2-methylbutane
d. 3-methylpentane
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c
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What is the approximate dihedral angle between the two methyl groups in the diequatorial conformation of trans-1,2-dimethylcyclohexane?
a. 180
b. 90
c. 60
d. 0
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c. 60 degrees
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What is the index of hydrogen deficiency (or degree of unsaturation) for the drug lidocaine, the molecule depicted below?
a. 3
b. 4
c. 5
d. 6
e. 7
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c. 5
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Which of these is not a true statement?
a. All bronsted lowry acids contain hydrogen
b. All lewis bases are also Bronsted Lowry bases
c. All lewis acids contain hydrogen
d. all lewis acids are electron deficient
e. According to the bronsted lowry theory water is both an acid and a base
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c. All lewis acids contain hydrogen
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What is the hybridization of carbon atoms labeled i-iii in the following structure?
H2C=C=CH2
i ii iii
a. i=sp; ii=sp; iii=sp
b. i=sp2; ii=p; iii=sp2
c. i=sp2; ii=sp; iii=sp2
d. i=sp2; ii=sp2; iii=sp2
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c. i=sp2; ii=sp; iii=sp2
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What is the Conjugate acid of ethanol?
a. CH3CH2O-
b. CH3CH2-
c. CH3CH2OH2+
d. CH3CH3
e. CH3OCH3
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c. CH3CH2OH2+
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Which of the following terms describes the reactivity of trimethylamine (CH3)3N?
a. Bronsted-Lowry acid and Lewis Acid
b. Lewis acid and not a Bronsted Lowry acid
c. Bronsted lowry base and lewis base
d. Lewis Base and not a bronsted lowry base
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c
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Bronsted Lowry Acid
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proton (H+ ion) donor
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Bronsted Lowry Base
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proton acceptor
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How many sigma bonds are there in ethene that are formed by s-sp2 overlap?
a. 6
b. 5
c. 4
d. 3
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c. 4
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What intermolecular interaction is not found in a flask contain only CH2CH2CH2CH2CH2OH?
a. Dispersion forces
b. Ion-ion
c. Hydrogen bonding
d. Dipole- dipole
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b. Ion-ion
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Which of the following species has an atom that has an unfilled valence shell of electrons?
a. Molecular hydrogen, H2
b. Hydroxide anion, HO-
c. Boron Trifluoride, BF3
d. Water, H3O+
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c. Boron Trifluoride, BF3
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Which of the following compounds has only 1 and 3 carbon atoms?
a. hexane
b. 2-methylpentane
c. 3-methlypentane
d. 2,3-dimethylbutane
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d. 2,3-dimethylbutane
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How many sigma bonds are there in ethene that are formed by s-sp3 overlap?
a. 7
b. 6
c. 5
d. 4
e. 3
f. 2
g. 1
h. 0
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h. 0
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According to the Bronstead-Lowry definition, a base is a(n)
a. Proton donor
b. Electron pair donor
c. Hydrogen ion acceptor
d. Electron pair acceptor
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c. Hydrogen ion acceptor
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Which of the following compounds can adopt a chair conformation in which there are no axial methyl groups?
a. cis-1,2-dimethylcyclohexane
b. cis-1,3dimethylcyclohexane
c. trans-1,3-dimethylcyclohexane
d. cis-1,4-dimethylcyclohexane
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b. cis-1,3dimethylcyclohexane
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Enantiomers are:
a. molecules that have a mirror image
b. molecules that have at least one stereogenic center
c. non-superposable molecules
d. non-superposable constitutional isomers
e. non-superposable molecules that are mirror images of each other
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e. non-superposable molecules that are mirror images of each other
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What is the most stable conformation of trans-1-tert-butyl-3-methylcyclohexane is the one in which:
a. the tert-butyl group is axial and the methyl group is equatorial
b. The methyl group is axial and the tert-butyl group is equatorial
c. both groups are axial
d. both groups are equatorial
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b. the methyl group is axial and the tert-butyl group is equatorial
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When the proton transfer reactions reach equilibrium there have been formed:
a. the weaker acid and the weaker base
b. the weaker acid and the stronger base
c. the stronger acid and the weaker base
d. the stronger acid and the stronger base
e. All proton transfers go to completion they are not equillibrium processes
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a. the weaker acid and the weaker base
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Which combination of reagents is the least effective in generation sodium ethoxide CH3CH2ONa?
a. CH3CH2OH + NaNH2
b. CH3CH2OH + NaOH
c. CH3CH2OOH + CH3Na
d. CH3CH2OH + HC(triplebond)CNa
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b. CH3CH2OH + NaOH
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Lewis Acid
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acid is an electron acceptor
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Lewis Base
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base is an electron donor
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Which of the following is a lewis acid but not a bronsted lowry acid?
a. CH3COOH
b. AlCl3
c. H2O
d. CH3OH
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b. AlCl3
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Which of the following statements is not true regarding pairs of enantiomers?
a. They have identical melting points
b. They have identical boiling points
c. They rotate plane polarized light in equal but opposite amounts
d. They react identically in chiral environments like a human body
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d. They react identically in chiral environments like a human body
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What is the aproximate dihedral angle between the two chlorine atoms in the diaxial conformation of trans-1,2-dichlorocyclohexane?
a. 30
b. 60
c. 120
d. 180
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d. 180
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How many electrons are there in the valence shell of the carbon atom or a methyl cation CH3+?
a. 3
b. 4
c. 5
d. 6
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d. 6
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Which of the following statements is not true regarding the conformation of substituted cyclohexanes?
a. ring inversion of cyclohexanes between two chair conformations takes place via a boat conformation
b. Substituted cyclohexanes are destablilized by 1,3-diaxial interactions
c. the boat conformation is more stable than the chair conformation
d. the relative amount of the two conformations of substituted cyclohexanes can be determined from the difference in strain energy
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c. the boat conformation is more stable than the chair conformation
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Considering the Equilibrium below which species represents the bronsted lowry bases?
PO4^3- + H2O <--> HPO4^2- + HO-
a. PO4^3- and H2O
b. PO4^3- and HPO4^2-
c. PO4^3- and OH-
d. H2O and OH-
e. H2O and HPO4^2-
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c
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How many electrons are there in the valence shell of the carbon atom of a methyl anion?
a. 4
b. 5
c. 6
d. 8
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c. 6
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Which of the following is a polar covalent bond?
a. Na-F
b. C-H
c. C-O
d. Cl-Cl
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c. C-O
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What is the approximate value of the H-C-H bond angles in a methyl anion, CH3-?
a. 90 degrees
b. 109 degrees
c. 120 degrees
d. 180 degrees
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b. 109 degrees
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Which of the following bonds has the smallest dipole moment?
a. C-O
b. C-N
c. C-N
d. O-H
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b. C-N
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The most stable conformation of 3-bromo-2-methylpentane viewed along the C2-C3 bond
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Anti
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Which of the following reactions of alkenes is not stereoselective?
a. Bromination (treatment with Br2 in CHCl3)
b. Acid-catalyzed hydration (treatment with aqueous H2SO4)
c. Hydrogenation (treatment with H3/Pt)
d. Bromohydrin formation (treatment with Br2, H2O)
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b. Acid-catalyzed hydration (treatment with aqueous H2SO4)
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As a consequence of the "leveling effect", which of the following is present in the highest concentration upon dissolution of H2SO4 in water?
a. H2SO4
b.H+
c.H3O+
d. HO-
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c.H3O+
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Which of the following is the definition of a pair of enantiomers?
a. A pair of structures that are superposable mirror images of one another
b. A pair of stereoisomers that are non-superposable mirror images of one another
c. A pair of stereoisomers that are not mirror images of one another
d. A pair of stereoisomers that have equal specific rotations
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b. A pair of stereoisomers that are non-superposable
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When cyclohexene is treated with OsO4, the spatial arrangement of the two hydroxyl groups in the product would be:
a. equitorial-equitorial
b. axial-axial
c. equitorial-axial
d.coplanar
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c. equitorial-axial
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Which of the following is the most nucleophilic?
a. sodium ethoxide
b. acetic acid
c. methanol
d. water
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a. sodium ethoxide
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What type of reaction mechanism accounts for the reaction of an alkene with aqueous acid to give an alcohol?
a. nucleophilic substitution
b. nucleophilic addition
c. radical addition
d. elimination
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b. nucleophilic addition
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Which of the following alkyl halides undergoes the fastest SN1 reaction with sodium cyanide, NaCN?
a. methyl iodide
b. ethyl iodide
c. 2-idopropane
d. tert-butyl iodide
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d. tert-butyl iodide
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Zaitsev's rule states that:
a. In electrophilic addition of an unsymmetrical reagent to an unsymmetrical alkene, the more positive portion of the reagent will become attached to the carbon of the double bond bearing the greater number of hydgron atoms
b. An equtorial substituent in cyclohexane results in a more stable conformation than if that substituent were axial
c. E2 reactions occur only if the B-hydrogen and leaving group can assume an anti-periplanar arrangement
d. When a reaction forms an alkene, and several possibilities exist, the more stable isomer is the one which predominates
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d. When a reaction forms an alkene, and several possibilities exist, the more stable isomer is the one which predominates
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Which statement is not true for a meso compound?
a. There are one or more planes of symmetry
b. A single molecule is identical to its mirror image
c. More than one stereogenic center must be present
d. The stereochemical labels (R & S) must be identical for each stereogenic center
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d. The stereochemical labels (R & S) must be identical for each stereogenic center
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What type of reactive intermediates is formed in the reaction of an alkene with Br2 to give the dibromide?
a. carbocation
b. carbanion
c. radial
d. cyclic bromonium ion
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d. cyclic bromonium ion
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The relationship between cis and trans isomers is an example of:
a. enantiomers
b. diastereomers
c. constitutional isomers
d. confromational isomers
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b. diastereomers
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Which of the following concepts explains why tertiary carbocations are more stable than primary and secondary carbocations?
a. electronegativity
b. resonance
c. hyperconjugation
d. the octet rule
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c. hyperconjugation
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Which of the following concepts explains Markovnikov's rule as applied to the addition of HBr to propene?
a. The relative stability of carbocations
b. The nucleophilicity of bromide anion
c. The acidity of HBr
d. The Aufbau principle
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a. The relative stability of carbocations
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Which of the following is a definition of the rate-limiting (or rate-determining) step of a reaction mechanism?
a. the first step
b. the last step
c. the step that crosses the highest energy barrier
d. the most exothermic step
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c. the step that crosses the highest energy barrier
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Which of the following concepts explains Markovnikov's rule as applied to the addition of HBr to propene?
a. the relative stability of carbocations
b. the nucleophilicity of bromide anion
c. the acidity of HBr
d. the aufbau principle
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a. the relative stability of carbocations
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What is the index of hydrogen deficiency of a compound with a molecular formula of C6H8?
a. 0
b. 1
c. 2
d. 3
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d. 3
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What type of reactive intermediate is formed in the reaction of an Alkene with Br2 and water to give a bromohydrin?
a. carbocation
b. carbanion
c. radical
d. cyclic bromonium ion
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d. cyclic bromonium ion
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Which of these compounds will react with aqueous H2SO4 as well as Br2?
a. CH3CH3CH=CHCH3
b. CH3CH2CH2CH=CH2
c. CH3CH3C=CCH3
d.(CH3)2CHC=CH
e. all of these
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e. all of these
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Which atomic orbitals overlap to form the carbon-carbon single bond of 1-propene?
a. 2s + sp
b. sp + sp2
c. sp + sp3
d. sp2 +sp3
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d. sp2 +sp3
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Which of the following reactions of cyclobutene would yield a meso product?
a. Reaction with H30+, H20
b. Reaction with Br2
c. Reaction with Cl2
d. Reaction with 1) OsO4 2)NaHSO3/H20
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d. Reaction with 1) OsO4 2)NaHSO3/H20
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Which of the following is not true regarding alkene?
a. Alkenes are nonpolar
b. alkene burn in air to give H2O and CO2
c. Alkene are high miscible with water
d. The strongest intermolecular force between alkenes is van der waals interactions
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c. Alkene are high miscible with water
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Which of the following is the definition of a pair of diastereomers?
a. a pair of structures that are superposable mirror image of one another
b. a pair of stereoisomers that are non-superposable mirror images of one another
c. a pair of stereoisomers that are not mirror images of one another
d. a pair of stereoisomers that have equal specific rotations
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c. a pair of stereoisomers that are not mirror images of one another
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Which of the following reactions of alkenes is stereoselective?
a. addition of HCl
b. hydrogenation (treatment with H2/Pt)
c. addition of HBr
d. acid-catalyzed hydration (treatment with aq H2SO4)
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b. hydrogenation (treatment with H2/Pt)
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Which of the following is the best definition of the activation energy for a reaction?
a. a difference in Gibbs free energy between the reactants and the transition state
b. a difference in Gibbs free energy between the reactants and the intermediate
c. a difference in Gibbs free energy between the reactants and the product
d. a difference in Gibbs free energy between the transition state and the product
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a. a difference in Gibbs free energy between the reactants and the transition state
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What is the approx value of the H-C-H bonds angle in ethene?
a. 90
b. 109
c. 120
d. 180
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c. 120
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The interaction of the pi bond of an alkene with an elctrophile can initially result in the formation of a species termed a pi complex. Which of these cannot combine with an alkene to form a pi complex?
a. H+
b.NH3
c.Ag+
d.Hg2+
e.BF3
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b.NH3
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What type of reactive intermediate is formed in the reaction of an Alkene with Br2 and water to give a bromohydrin?
a. carbocation
b. carbanion
c. radical
d. cyclic bromonium ion
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d. cyclic bromonium ion
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In general when the addition of an unsymmetrical electrophilic reagent to an unsymmetrical alkene forms the product predicted by Markovnikov's rule that occurs because:
a. the product is statistically favored
b. steric hindrance favors its formation
c. it is formed via the more/most stable carbocation
d. it is the more/most stable product
e. all of the reasons above
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c. it is formed via the more/most stable carbocation
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Which alkene would you expect to be most react toward acid-catalyzed hydration?
a. 1 pentene
b. trans-2-pentene
c. cis-2-pentene
d. 2-methyl-1-butene
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d. 2-methyl-1-butene
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Which of the following reactions of alkenes is not stereoselective?
a. cis-2-pentene Br2->
b. trans-2-butene Br2/H2o->
c. 1-methylcyclohexene 1) OsO4 2)NaHSO3/H2O ->
d. trans-2-hexene HBr->
e. 2-methyl-2-heptene H2,Pd->
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d. trans-2-hexene HBr->
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which of the following is the most nucleophilic?
a. sodium ethoxide
b. acetic acid
c. methanol
d. water
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a. sodium ethoxide
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What type of reactive intermediate is formed in the reaction of an alkene with Br2and water to give a 1,2-bromo alcohol(bromohydrin)?
a. cyclic bromium ion
b. carbanion
c. carbocation
d. radical
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a. cyclic bromium ion
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Which concept below best explains the fundamental basis behind Markovnikov's rule?
a. Electronegativity
b. resonance
c. hyperconjugation
d. the octet rule
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c. hyperconjugation
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Which of the following statements is not true regarding the SN2 reaction of (R)-2-bromobutane with sodium methoxide?
a. the reaction proceeds with inversion of the configuration
b. the rate is proportional to the concentration of sodium methoxide
c. the rate is proportional to the concentration of (R)-2-bromobutane
d. the rate is not proportional to the concentration of sodium methoxide
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d. the rate is not proportional to the concentration of sodium methoxide
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