OC-2021 Flashcards
Dipoledipole interactions are present in _____.
A. HCl B. C6H6 C. CH4 D. NaCl
HCl
Non-polar atoms and molecules condense due to _____.
A. iondipole interaction
B. polarizability dispersion forces
C. van der Waals forces
D. dipoledipole attraction
B. van der Waals forces
A compound having a permanent dipole moment is _____.
A. CO2
B. H2
C. CH4
D. CO
CO
“dipole moment” = polar
Which element can take part in hydrogen bonding?
A. F
B. O
C. N
D. all of them
D. all of them
all are highly electronegative elements
Polarizability is highest for _____.
A. CH4 B. H2 C. CCl4 D. H2S
C. CCl4
A compound which hydrogen bonds is _____.
A. BeH2
B. CH4
C. CH3COOH
D. C2H6
C. CH3COOH
The force due to hydrogen bonding must be overcome in the boiling of _____.
A. CH3OCH3
B. NH3
C. SbH3
D.C2H5OC2H5
B. NH3
Note: determine which one will undergo hydrogen bonding
other options are dipole dipole and vdw
The hydrocarbon having the lowest boiling point is _____.
A. C4H10
B. CH4
C. C6H6
D. C2H6
B. CH4
low molecular size = low BP
Which of the following has the lowest boiling point?
A. CH3COCH3
B. CH3OCH3
C. CH3COOH
D.CH3CHO
B. CH3OCH3
an ether.
Other options are DD, HB, and DD which is higher in BP
Note. DRAW
Arrange the following according to increasing boiling point:
W= methyl acetate
X= butanal
Y= n-butyl alcohol
Z = butanoic acid
methy acetate < butanal < n-butyl alcohol < butanoic acid
Which of the following has the lowest boiling point?
A. o-hydroxynitrobenzene
C. p-hydroxynitrobenzene
B. m-hydroxynitrobenzene
D. p-hydroxybenzoyl chloride
o-hydroxynitrobenzene
BP: mono < ortho < meta < para
Which of the following statements is correct?
A. The greater the molecular weight, the lower the b.p
B. The greater the molecular attraction, the higher the b.p
C. The greater the molecular attraction, the lower the HV
D. The smaller the molecular weight, the higher the b.p
The greater the molecular attraction, the higher the b.p
Melting Point
I (aldehyde) – Lowest melting point.
IV (meta-nitrobenzoic acid) – Slightly higher due to hydrogen bonding.
II (para-nitrobenzoic acid) – Stronger hydrogen bonding, para position increases symmetry and packing efficiency.
III (sodium salt) – Highest due to ionic bonding.
The vapor pressure of a liquid depends on the _____.
A. amount of liquid
C. temperature of the liquid
B. volume of the liquid
D. surface area of the liquid
C. temperature of the liquid
A liquid having a higher vapor pressure will have _____.
A. higher molecular weight
C. higher boiling point
B. lower boiling point
D. higher surface area
B. lower boiling point
Which of the following properties indicates very strong intermolecular forces in liquids?
A. very low surface tension
C. very low boiling point
B. very low critical temperature
D. very low vapor pressure
D. very low vapor pressure
Rank the following compounds in the order of increasing basicity:
I.p-nitroaniline
II. p-aminobenzaldehyde
III. N-methylaniline
IV. p-methylaniline
I.p–nitroaniline
II. P-aminobenzaldehyde
IV p-methyaniline
III. N-methylaniline
Arrange according to increasing acidity
I. methanol
II. ethanol
III. Phenol
IV. p-nitrophenol
V. p-bromophenol
ethanol < methanol < phenol < p-bromophenol
Arrange the following according to increasing acid strengths:
W= benzoic acid
Y= 4-cyanobenzoic acid
X= 4-methoxybenzoic acid
Z = 4-methylbenzoic acid
XZWY
methoxy < methyl < benzoic < cyano
: X (–OCH3) < Z (–CH3) < W (no group) < Y (–CN).
- Which of the following molecules has a linear geometry?
a. water (H2O)
c. carbon dioxide (CO2)
b. ammonia (NH3)
d. boron trifluoride (BF3)
c. carbon dioxide (CO2)
The most stable among the following free radicals is
a. CH3 ?
b. (CH3)3C ?
c. (CH3)2CH ?
d. (CH3)2CHCH2
c. (CH3)2CH ?
high no. of C atoms = low stability
high no. of branching = high stability
The stability of free radicals follows the order: tertiary > secondary > primary > methyl
- Which of the following is TRUE about cis and trans alkenes?
a. Cis alkenes are less polar.
b. Cis alkenes have higher boiling points.
c. Trans alkenes are more polar.
d. Trans alkenes have higher boiling points.
b. Cis alkenes have higher boiling points.
Cis alkenes are more polar than trans alkenes due to the arrangement of substituents on the same side of the double bond, which creates a net dipole moment. This leads to stronger intermolecular forces (dipole-dipole interactions) in cis alkenes, resulting in higher boiling points compared to their trans counterparts. Trans alkenes, on the other hand, tend to cancel out dipoles due to the symmetry, making them less polar and giving them lower boiling points.
- How many distinct acyclic compounds have the formula C5H10?
a. 3
b. 4
c. 5
d. 6
5
- Which compound will rapidly decolorize bromine in CHCl3?
a. hexane
c. 1-hexene
b. benzene
d. cyclohexane
c. 1-hexene
- All of the following statements concerning benzene, C6H6, are true EXCEPT
a. Each carbon is sp2 hybridized.
b. Each carbon atoms forms three sigma bonds.
c. Pi electrons are delocalized over all six carbon atoms.
d. Benzene forms cis and trans isomers when it reacts.
Benzene forms cis and trans isomers when it reacts.
- What is the product from the Friedel-Crafts alkylation of nitrobenzene?
a. ortho-nitrotoluene
c. para-nitrotoluene
b. meta-nitrotoluene
d. ortho-nitrotoluene and para-nitrotoluene
meta-nitrotoluene
- Which of the following is TRUE for EAS?
I. Sulfonation uses both nitric and sulfuric acids.
II. The intermediate carbocation in EAS reactions is resonance-stabilized.
III. Halogenation reactions require the use of Lewis acid catalysts to make X – X bond more polar.
II and III
I is FALSE: ang gamit is sulfuric acid and sulfur trioxide
- Which chloroalkane undergoes substitution with OH? exclusively by an SN1 mechanism?
a. (CH3)3CCl
b. (CH3)2CHCH2Cl
c. CH3CH2CHClCH3
d. CH3CH2CH2CH2Cl
a. (CH3)3CCl
SN1 - tertiary secondary
- What is the role of hydroxide ion in this reaction?
CH3CH2CH2CH2Br + OH? ? CH3CH2CH2CH2OH + Br?
a. oxidizing agent c. catalyst
b. Lewis acid d. nucleophile
d. nucleophile
attacks compound and replace bromine
donates electron pair to bond with carbon
- Which of the following will react with HBr?
a. 1-butanol
b. 2-butanol
c. 2-methyl-1-propanol
d. 2-methyl-2-propanol
c. 2-methyl-1-propanol
tertiary alcohol reacts fastest
- Which of the following is the simplest ketone?
a. acetone
b. lactone
c. cyclohexanone
d. ethyl methyl ketone
acetone
- Evolution of gas was observed when an unknown organic compound is treated with aqueous Na2CO3. The compound is likely a/an
a. ester
b. alkane
c. alcohol
d. carboxylic acid
carboxylic acid
“Na2CO3
- A student wishes to prepare ethyl acetate from the reaction of ethanol and acetic acid. To be successful, this reaction requires
a. an acidic catalyst
b. a basic catalyst
c. an oxidizing agent
d. a reducing agent
an acidic catalyst
All of the following can form hydrogen bonds EXCEPT
a. aniline
b. ethyl amine
c. isopropyl amine
d. trimethyl amine
d. trimethyl amine
hydrogen bonding: if may NH, OH, and FH
Trimethyl amine (N(CH₃)₃) cannot form hydrogen bonds because there are no hydrogen atoms attached to the nitrogen that can participate in hydrogen bonding. Hydrogen bonding typically occurs when a hydrogen atom is bonded to a highly electronegative atom like nitrogen, oxygen, or fluorine.
- A chemist wishes to separate benzoic acid from 4-hydroxybenzaldehyde. Which is the best method to achieve this separation?
a. Partitioning the mixture between diethyl ether and water
b. Partitioning the mixture between diethyl ether and 1 M aqueous NaHCO3
c. Partitioning the mixture between diethyl ether and 1 M aqueous NaOH
d. Partitioning the mixture between diethyl ether and 1 M aqueous HCl
b. Partitioning the mixture between diethyl ether and 1 M aqueous NaHCO3
- All of the following are properties of an organic solvent for extraction EXCEPT
a. dissolve the desired substance
b. react with the desired substance
c. not react or be miscible with water
d. have a low boiling point so it can be easily removed at a later purification step
react with the desired substance
- This must be done before discarding any liquid after separation (of the liquids) is seen inside the separatory funnel.
a. shaking
b.venting
c. salting out
d. testing the aqueous and organic layers
testing the aqueous and organic layers
“after separation”
- This is used to remove trace amounts of water in organic solutions. This can be added to the pooled organic layers before removal of the organic solvent.
a. drying agent
b. boiling stone
c. seed crystal
d. decolorizing carbon
a. drying agent
- All of the following are steps during recrystallization EXCEPT
a. Dissolve the sample in a minimum amount of hot solvent.
b. Filter the hot solution using a stemless funnel.
c. Cool down the filtrate abruptly to recover the crystallized product quickly.
d. Wash the crystallized product with cold solvent during suction filtration.
Cool down the filtrate abruptly to recover the crystallized product quickly.
- This is done to remove colored impurities in a solution containing the crude sample.
a. evaporation of solvent
b. addition of drying agent
c. addition of decolorizing carbon
d. scratching the sides of the flask
c. addition of decolorizing carbon
“removed colored impurities”
- Purified solid crystals have
a. low melting points
b. high melting points
c. wide melting point ranges
d. narrow melting point ranges
d. narrow melting point ranges
Purified solid crystals= narrow melting point range because they are more uniform in composition, without impurities.
- A student isolated solid caffeine from tea leaves. Which experiment will be most useful in assessing the purity of the isolated caffeine?
a. combustion analysis
b. melting point determination
c. titration with standard NaOH
d. determination of the lambda max of the solution
melting point determination
“PURITY”
method used to assess the purity of a solid compound.
- It allows for many successive distillations to take place at once. It contains indentations or a packing material with lots of surface area.
a. adapter
b. condenser
c. round bottom flask
d. fractionating column
d. fractionating column
- In order to provide heat at a temperature of 200°C to solutions containing organic reagents, which of the following is the most suitable?
a. heat using a water bath
b. heat using a sand bath
c. heat with Bunsen burner
d. heat with hotplate with stirring
b. heat using a sand bath
- Which of the following can promote even boiling?
a. stones
b. chips
c. stir bars
d. All of the above
all of the above
- Where should a thermometer be placed to determine the boiling point of the distillate?
a. Inside the distilling flask and it should be just below the side arm of the flask
b. Inside the distilling flask and it should be immersed in the mixture being distilled
c. Inside the receiver
d. Inside the adapter
Inside the distilling flask and it should be just below the side arm of the flask
A 1:1 mixture of pentane and hexane is separated by fractional distillation. At what temperature does the first drop of condensate appear on the thermometer?
a. less than 36°
b. at 36°
c. between 36° and 69°
d. above 69°
at 36
pentane: 36C
hexane : 69C
- Which statement best describes the results of attempted separation by fractional distillation of cis-1,2-dichloroethene and trans-1,2-dichloroethene?
a. The two isomers can be separated by fractional distillation, with cis isomer boiling at the lower temperature.
b. The two isomers can be separated by fractional distillation, with trans isomer boiling at the lower temperature.
c. The two isomers cannot be separated by fractional distillation because both isomers have the same boiling point.
d. The two isomers cannot be separated by fractional distillation because they interconvert rapidly at the temperatures at which they distill.
The two isomers can be separated by fractional distillation, with trans isomer boiling at the lower temperature.
Cis: polar-high BP
trans: nonpolar: low BP
- What is the main purpose of heating under reflux?
a. To provide a very high temperature so that slow reactions occur at faster rates.
b. To increase the rate of evaporation of the solvent to increase the product yield.
c. To heat the reaction mixture in a solvent at a constant temperature without the loss of any reagents.
d. None of the above.
To heat the reaction mixture in a solvent at a constant temperature without the loss of any reagents.
- A reaction vessel is to be cooled to -77°C after refluxing. Which of the following can be used?
a. ice bath
b. freezer
c. acetone/dry ice
d. crushed ice with salt
c. acetone/dry ice
- A student would like to separate the various components of a sample of ink in the laboratory. Which of the following techniques would be most suitable for him to use?
a. filtration
b. titration
c. distillation
d. paper chromatography
paper chromatography
- Methyl t-butyl ether (MTBE) is a controversial gasoline additive. Which of the following techniques would be best to measure quantitatively trace amounts of MTBE in contaminated groundwater?
a. capillary electrophoresis
b. gas chromatography
c. atomic absorption spectroscopy
d. fluorescence spectroscopy
b. gas chromatography
- The efficiency of chromatographic columns increases as (in the choices: N = plate count, H = plate height)
a. N becomes greater and as H becomes smaller
b. N becomes lesser and H becomes larger
c. Both N and H becomes constant
d. None of the above
N becomes greater and as H becomes smaller
- The distribution constant is the ratio of the concentration of a solute in the stationary phase to its concentration in the mobile phase. Benzene has a lower distribution constant than cyclohexane. Which will elute first during a chromatographic analysis?
a. benzene
b. cyclohexane
c. both will elute at the same time
d. neither will be eluted
benzene
- In anion-exchange chromatography,
a. the column contains negatively-charged beads where positive species bind.
b. the column contains positively-charged beads where negative species bind.
c. the column contains both positive and negatively-charged beads where species bind depending on their net charge.
d. None of the above
the column contains positively-charged beads where negative species bind.
- Ion-exchange chromatography is based on
a. electrostatic attraction
b. electrical mobility of ionic species
c. electrical conductance of species
d. partitioning of a species between phases
a. electrostatic attraction
- It is a type of size-exclusion chromatography, that separates analytes on the basis of size, typically in organic solvents. The technique is often used for the analysis of polymers.
a. gel filtration chromatography
b. gel permeation chromatography
c. ion-exchange chromatography
d. hydrophobic interaction chromatography
b. gel permeation chromatography
- Which of the following chromatographic techniques does not exist?
a. liquid-liquid chromatography
b. solid-solid chromatography
c. gas-liquid chromatography
d. gas-solid chromatography
b. solid-solid chromatography
- Quantitative analysis can be achieved by which of the following technique/s?
I. Thin layer chromatography
II. Gas chromatography
III. Column chromatography
IV. Ion-exchange chromatography
a. II only
b. I and II only
c. II and III only
d. I, II, III, and IV
b. I and II only
- An ideal detector in HPLC has the following desirable features EXCEPT
a. high detection limit
b. linear response over a wide range of solute concentrations
c. sensitive for all solutes or selective for a specific class of solutes
d. insensitive to a change in flow rate or temperature
high detection limit
- In the analysis of a mixture by gas chromatography, which of the following gives the best clue as to whether the components can be analyzed with any degree of accuracy?
a. column length
b. retention times
c. column temperature
d. flow rate of the carrier gas
b. retention times
- The determination of the equilibrium constant of a colored species can be done via which technique?
a. conductance
b. ion-exchange
c. electrophoresis
d. spectrophotometry
d. spectrophotometry
- All proteins absorb electromagnetic radiation of wavelength around 190 nm, which corresponds to a ?? ? ??? excitation in the protein molecule. In which region of the spectrum is this wavelength found?
a. X-ray
b. ultraviolet
c. visible
d. microwave
b. ultraviolet
- For aqueous solutions of which of the following substances could the concentration be determined by visible spectrophotometry?
a. Cr(NO3)3
b. KMnO4
c. Zn(NO3)2
d. Both A and B
d. Both A and B
Cr(NO3)3 and KMnO4
because they contain transition metal ions (Cr³⁺ and MnO₄⁻, respectively) that absorb visible light, giving their solutions distinctive colors (Cr³⁺ is typically green or violet, and MnO₄⁻ is deep purple)
- What is the correct order of stages during a mass spectroscopic analysis?
a. ionization – vaporization – acceleration – deflection – detection
b. vaporization – ionization – deflection – detection – acceleration
c. vaporization – ionization – acceleration – deflection – detection
d. acceleration – deflection – vaporization – ionization – detection
vaporization – ionization – acceleration – deflection – detection
- IR spectroscopy is useful for determining certain aspects of the structure of organic molecules because
a. All molecular bonds absorb IR radiation.
b. IR peak intensities are related to molecular mass.
c. Vibrational transitions are related to spin-spin coupling.
d. Most organic functional groups absorb in a characteristic region of the IR spectrum.
Most organic functional groups absorb in a characteristic region of the IR spectrum.
- A compound with the molecular formula C7H14O has an IR absorption at 1715 cm?1. Which of the following is responsible for this absorption?
a. C – X
b. C = C
c. C = N
d. C = O
d. C = O
- All of the following absorptions can be seen above 3000 cm?1 in an IR spectrum EXCEPT
a. C – H
b. C – C
c. O – H
d. N – H
b. C – C
- According to the Department of Trade and Industry – Bureau of Philippine Standards (DTI-BPS), what color designations correspond to dry chemical (ABC) type of fire extinguisher?
a. red body, white band
b. red body, black band
c. red body, blue band
d. light green body, white band
a. red body, white band
- A ? bond is the result of the
A. Overlap of two s orbitals
B. Overlap of an s and a p orbital
C. sidewise overlap of two s orbitals
D. sidewise overlap of two parallel p orbitals
E. head to head overlap of two p orbitals
sidewise overlap of two parallel p orbitals
- Which of the following statements about carbon is NOT correct?
A. Carbon forms strong covalent bonds to itself, allowing chains and rings to be made.
B. Carbon expands its valence shell to accommodate more than eight electrons and thus forms double and triple bonds.
C. Carbon and hydrogen have similar electronegativity and form strong bonds to each other, thus avoiding the high reactivity shown by metal hydrides.
D. Carbon forms strong covalent bonds to elements like nitrogen and oxygen because it does not have lone pairs of valence electrons to destabilize the bonds.
E. All of the above statements are correct.
Carbon expands its valence shell to accommodate more than eight electrons and thus forms double and triple bonds.
- How would the bond strength of the C = C double bond in an alkene compare to that of a C – C single bond in the corresponding alkane?
A. The double bond would have the same strength as the single bond.
B. The double bond would have exactly twice the strength of the single bond.
C. The double bond would have more than twice the strength of the single bond.
D. The double bond would be stronger than, but less than twice as strong as the single bond.
E. The double bond would have weaker strength than that of the single bond.
The double bond would be stronger than, but less than twice as strong as the single bond.
- The most stable among the following free radicals is
A. CH3·
B. (CH3)3C·
C. (CH3)2CH·
D. (CH3)3CHCH2·
E. CH3CH2·
(CH3)3C·
This is a tertiary radical, which is stabilized by three adjacent methyl groups through hyperconjugation and inductive effects. This is highly stable.
- How is the rate affected when the concentration of the nucleophile is doubled in an SN1 reaction?
A. The rate is halved.
B. The rate is doubled.
C. The rate quadruples.
D. The rate is unchanged.
E. The rate triples.
The rate is unchanged.
- What is the dominant mechanisms for the reaction of 1-chloropentane and potassium tert-butoxide?
A. E1
B. E2
C. SN1
D. SN2
E. Can be E1 or SN1
D. SN2
- Which of these statements is TRUE for an E2 reaction?
A. It involves a two-step mechanism.
B. It involves a very reactive intermediate.
C. The rate of the reaction depends on the concentration of the base.
D. The rate of the reaction increases in polar solvents.
e. All of the above statements are true about an E1 reaction.
The rate of the reaction depends on the concentration of the base.
- one step
- for less polar
- What is the order of acidity of the four compounds given (strongest to weakest)?
I. CH3CH2COOH
II. CH3CH2CH2OH
III. C6H5OH
IV. CH3C?CH
I, III, II, IV
carboxylic acid > phenol > alkyne > alcohol
- Which of the following is the correct order of acidity of the benzoic acids?
I – benzoic acid
II – para-nitrobenzoic acid
III – para-methylbenzoic acid
II > I > III
nitro group = highest (electron withdrawing)
methyl group = lowest (electron donating)
- What is the common name of (CH3CH2CH2)3N?
A. Propylamine
B. N-propylpropanamine
C. tripropylamine
D. N,N-dripropylpropanamine
E. tert-propylamine
tripropylamine
- Arrange the following amines in order of decreasing basicity?
I – p-nitroaniline
II – para-chloroaniline
III – para-methylaniline
III, II, I
Para-methylaniline (III): The methyl group (-CH?) is an electron-donating group, which increases the electron density on nitrogen, enhancing the basicity.
- The separation of ions in a mass spectrometer is fully determined by the
A. Size of the ions
B. Mass of the ions
C. number of the ions
D. mass-to-charge ratio of ions
E. strength of ions
mass-to-charge ratio of ions
- All peaks in the mass spectrum of chlorobenzene are accompanied by a smaller peak one mass unit higher. This peak is due to which of the following?
A. Presence of a 13C
B. Presence of a 36Cl
C. capture of a proton
D. capture of a hydrogen atom
E. presence of a 14C
Presence of a 36Cl
- In this solid sample treatment technique, the finely ground solid sample is mixed with a mineral oil to make a thick paste which is then spread between IR transmitting windows.
A. Solid films
B. Pressed pellet
C. mull technique
D. solids run in solution
E. reflectance technique
mull technique
- Which of the following bonds would be expected to have the highest frequency stretch?
A. Carbon-carbon triple bond
B. Carbon-carbon single bond
C. carbon-carbon double bond
D. carbon-bromine single bond
E. carbon-chlorine bond
Carbon-carbon triple bond
“frequency”
highest frequency is proportional to bond order
- A strong signal at 1700 cm-1 in an IR spectrum indicates the presence of a(n)
A. Ether
B. amine
C. alcohol
D. carbonyl
E. triple bond
carbonyl
- Which of the following intermediates is pyramidal in shape?
A. H2C:
B. H3C:-
C. H3C+
D. HC?C:-
E. HC=C:
H3C:-
- Non-polar atoms and molecules condense due to
A. Ion – dipole interaction
B. Van der Waals forces
C. polarizability dispersion forces
D. dipole – dipole attraction
E. electrostatic interaction
Van der Waals forces
- A compound with hydrogen bonds is
A. BeH2
B. CH4
C. CH3COOH
D. C2H6
E. CH3OCH3
C. CH3COOH
- Which of the following has the lowest boiling point?
A. CH3COCH3
B. CH3OCH3
C. CH3COOH
D. CH3CHO
E. CH3CH2CH3
CH3CH2CH3
- Arrange the following according to increasing boiling point:
W = methyl acetate
X = butanal
Y = n-butyl alcohol
Z = butanoic acid
W = methyl acetate
X = butanal
Y = n-butyl alcohol
Z = butanoic acid
- Which of the following statements is correct?
A. The greater the molecular weight, the lower the boiling point.
B. The greater the molecular attraction, the higher the boiling point.
C. The greater the molecular attraction, the lower the boiling point.
D. The smaller the molecular weight, the higher the boiling point.
E. The greater the molecular weight, the higher the boiling point.
The greater the molecular attraction, the higher the boiling point.
- The boiling point of a liquid depends on
A. external pressure
B. molecular attraction
C. molecular weight
D. vapor pressure
E. none of the given
molecular attraction
- Which of the following factors will not affect the rate of vaporization of the liquid?
A. Temperature
B. amount of liquid
C. intermolecular forces
D. surface area
E. pressure
amount of liquid
- The Lucas test is used to distinguish small (7 or fewer carbons) 1º, 2º and 3º alcohols. The alcohol to be tested is added to a solution of anhydrous ZnCl2 in conc. HCl at room temperature. Which of the following statements is not correct?
A. 1º-alcohols dissolve, but do not react
B. 3º-alcohols react quickly to give an insoluble alkyl chloride
C. 3º-alcohols rapidly dehydrate, and the gaseous alkene bubbles out of the test solution
D. 2º-alcohols dissolve and react slowly to give an insoluble alkyl chloride
3º-alcohols rapidly dehydrate, and the gaseous alkene bubbles out of the test solution
- Which of the following isomeric chlorides will undergo SN2 substitution most readily?
A. 4-chloro-1-butene
B. 1-chloro-1-butene (cis or trans)
C. 1-chloro-2-butene (cis or trans)
D. 2-chloro-1-butene
1-chloro-2-butene (cis or trans)
- Benzene owes its unusual stability to
A. pi electron delocalization over and above the six-carbon ring
B. alternating single and double bonds
C. stereochemistry
D. carbon being sp2 hybridized
E. cyclic and planar
pi electron delocalization over and above the six-carbon ring
- Benzene and its derivatives undergo substitution reactions instead of addition reactions because
A. the integrity of the benzene ring and the stable pi-bonding pattern remains intact
B. the hydrogens of benzene are relatively loosely bound
C. the benzene ring is sterically crowded hence only substitution can occur
D. the benzene ring is electron rich
E. the benzene ring is inert
the integrity of the benzene ring and the stable pi-bonding pattern remains intact
- A tertiary carbocation (carbonium ion) is more stable than either a secondary or primary carbocation because …
A. it carries three positive charges
B. it has a pyramidal configuration
C. it has a trigonal planar configuration
D. it possesses three electron-donating substituent groups
it possesses three electron-donating substituent groups
- Which of the following is both the correct bond angle and molecular geometry around a carbon atom with four single bonds?
A. 120°, tetrahedral
B. 120°, planar
C. 109.5°, tetrahedral
D. 109.5°, planar
E. 109.5°, square planar
C. 109.5°, tetrahedral
- The functional group for organic acids is the
A. Hydroxyl group
B. Amine group
C. carbonyl group
D. carboxyl group
E. amide group
carboxyl group
- The general formula for an ester is
A. ROR’
B. RCOOH
C. RCOR’
D. RCOOR’
E. RCOR’
RCOOR’
- How many electrons are shared in a triple bond?
A. 1
B. 2
C. 6
D. 4
E. 3
C. 6
- Which of the following is the product from the dehydration of an alcohol?
A. alkane
B. alkene
C. aldehyde
D. aldehyde
E. alkyne
alkene
- The carbonyl group of aldehydes and ketones is very reactive because
A. the -C=O bond is electron-rich
B. the oxygen has two nonbonding pairs
C. the -C=O bond is polar
D. all of these
E. none of these
D. all of these
- An example of a trihydric alcohol is
A. Ethyl alcohol
B. glycol
C. glycerol
D. isopropyl alcohol
E. carbinol
glycerol
chemical formula C?H?O?. It has three hydroxyl groups, one attached to each carbon in a three-carbon chain.
- An ester used as banana flavoring.
A. Ethyl methanoate
B. Pentyl ethanoate
C. methyl pentanoate
D. octyl ethanoate
E. isoamyl acetate
isoamyl acetate
- An inorganic ester that lowers blood pressure.
A. Ethyl nitrate
B. ethyl sulfate
C. pentyl nitrate
D. glyceryl trinitrate
E. nitrooxypropyl ester
glyceryl trinitrate
- The acid secreted by ants.
A. Methanoic acid
B. ethanoic acid
C. propanoic acid
D. butanoic acid
E. acetic acid
Methanoic Acid = Formic Acid
- The test for the presence of methyl carbonyl.
A. Benedict’s test
B. Fehling’s test
C. Haloform test
D. Tollen’s test
E. Iodine test
Haloform test
- What are the most likely products in the reaction between CH3CH2CH2OH and HI?
A. CH3CH2CH2I and H2O
B. CH3CH2CH3 and HOI
C. CH3OH and CH3CH2I
D. ICH2CH2CH2OH and H
E. ICH2CH2CH2I
CH3CH2CH2I and H2O
- All of these are aromatic compounds except
A. hexane
B. toluene
C. p-dichlorobenzene
D. naphthalene
E. anthracene
hexane
This is an aliphatic hydrocarbon (a straight-chain
. It does not have a cyclic structure or the characteristics of aromaticity.
- Fats and oils are formed from the combination of fatty acids with what other compound?
A. cholesterol
B. glucose
C. glycerol
D. phenol
E. vitamins
glycerol
Glycerol has three hydroxyl groups (-OH), and each of these can react with a fatty acid, which has a carboxyl group (-COOH).
- The H–C–O bond angle in H2C=O (formaldehyde) is approximately
A. 90°
B. 109°
C. 120°
D. 180°
E. 103°
C. 120°
Cyclohexane and water can be separated by using a separatory funnel. Which property contributes to this separation?
A. Cyclohexane and water are immiscible.
B. Cyclohexane has a lower viscosity than water.
C. Cyclohexane has a greater molar mass than water.
D. Cyclohexane has a greater vapor pressure than water
Cyclohexane and water are immiscible.
- Which solute is least soluble in water?
A. 1-butanol
B. ethanol
C. methanol
D. 1-propanol
1-butanol
- Purification techniques for solid product include the following except
A. Recrystallization
B. Sublimation
C. distillation
D. chromatography
C. distillation
- Filtration devices include the following except
A. Filter paper
B. glass wool
C. cotton plug
D. silica gel
E. gypsum
E. gypsum
What are the selection criteria for solvent in recrystallization?
A. The desired compound should be soluble in the hot solvent (approximately 1g/20 mL) and insoluble in the cold solvent (room temperature).
B. Impurities should either be insoluble in the solvent at all temperature or must remain in solution in the cold solvent.
C. Boiling point of the solvent must be low enough so that it can readily be removed from the crystals.
D. The boiling point of the solvent should be lower that the melting point of the solid being purified. Some solids decompose at their melting points.
E. All of the above.
E. All of the above.
- For which of the following situations is it appropriate to perform a recrystallization?
A. to purify an impure liquid
B. to purify an impure solid
C. The melting point of a compound is sharp and agrees with the literature value
D. An impure solid is soluble in all possible recrystallization solvents that are available at room temperature
to purify an impure solid
- Vacuum distillation is appropriately used for the following liquids:
A. Miscible liquids with boiling points lower than 150°C at 1 atm and difference in boiling points should be 25 to 40°C.
B. Miscible liquids with boiling points higher than 150°C at 1 atm and the difference should be 25 and 40°C.
C. Miscible liquids with difference in boiling points is less than 25 to 40°C.
D. Immiscible liquids
Miscible liquids with boiling points higher than 150°C at 1 atm and the difference should be 25 and 40°C.
The following are sources of errors in melting point determination except
A. Wet crystals
B. Uneven packing of crystals inside the capillary tube
C. crystals packed more than 2 mm
D. rapid increase of temperature
E. all are sources of errors
all are sources of errors
- Which of the following is a difference between benzene and cyclooctatetraene?
A. Benzene reacts rapidly with bromine and cyclooctatetraene does not.
B. Benzene contains sp2-hybridized carbon atoms and cyclooctatetraene does not
C. Benzene has the formula CnHn and cyclooctatetraene does not.
D. Benzene is planar and cyclooctatetraene is not.
Benzene is planar and cyclooctatetraene is not.
- Which of the numbered carbons in nicotine is chiral (stereogenic)?
A. 1
B. 2
C. 3
D. 4
B. 2
- Which substance can exist in boat and chair configurations?
A. Benzene
B. cyclohexane
C. naphthalene
D. cyclopentadiene
B. cyclohexane
- Which statement best describes the structure of the allene molecule, H2C=C=CH2?
A. The C atoms form an angle of 120° and the H atoms lie in the same plane as the C atoms.
B. The C atoms form an angle of 120° and the H atoms lie in a plane perpendicular to that of the C atoms.
C. The C atoms form an angle of 180° and the four H atoms lie in the same plane.
D. The C atoms form an angle of 180° and the two CH2 groups are perpendicular to one another.
The C atoms form an angle of 180° and the two CH2 groups are perpendicular to one another.
- The conjugate base of acetic acid is
A. HCOOH
B. NH3
C. CH3COO?
D. OH?
C. CH3COO?
- Which of the following is the Bronsted-Lowry base in the following reaction?
CH3O- + NH3—>CH3OH + NH -
A. CH3O-
B. NH3
C. CH3OH
d. NH -
A. CH3O-
- A hydrocarbon molecule is considered to be saturated if the molecule contains
A. single covalent bonds, only
B. a triple covalent bond
C. a double covalent bond, only
D. single and double covalent bonds
single covalent bonds, only
What occurs when liquid CH2F2 evaporates?
I. Dispersion forces are overcome.
II. Dipole-dipole forces are overcome
III. Covalent bonds are broken.
A. II only
B. III only
C. I and II only
D. I, II and III
C. I and II only
Evaporation involves only the breaking of intermolecular forces (dispersion and dipole-dipole forces) between molecules, not the intramolecular covalent bonds that hold the atoms together within the molecule.
- Estimate the enthalpy of combustion of methane in kJ.mol-1.
CH4(g) + 2O2(g) –> CO2(g) + 2H2O(g)
A. 668
B. 540
C. –540
D. –668
D. –668
?H=Total Bonds Broken?Total Bonds Formed
- How many structural isomers have the formula C5H12?
A. 2
B. 3
C. 4
D. 5
B. 3
- Enantiomers are?
A. stereoisomers having non-identical mirror image configurations
B. stereoisomers that do not have non-identical mirror image configurations
C. stereoisomers having a mirror plane of symmetry
D. achiral stereoisomers
stereoisomers having non-identical mirror image configurations
- A racemic mixture has equal amounts of
A. alkanes and alkenes.
B. cis and trans isomers.
C. functional group isomers.
D. enantiomers.
enantiomers.
- Which of the following statements is not generally correct?
A. endothermic reactions have larger energies of activation than exothermic reactions
B. the rate of a reaction is proportional to its activation energy
C. the rate of a reaction generally increases as the temperature is raised
D. all reactions in which bonds are broken and formed have a significant activation energy
endothermic reactions have larger energies of activation than exothermic reactions
- Which statement about free radicals is incorrect?
A. Free radicals contain an unpaired electron.
B. Radicals are believed to be involved in degenerative diseases and cancers.
C. They are formed by heterolytic cleavage of bonds.
D. Radicals can either be neutral or ionic.
They are formed by heterolytic cleavage of bonds.
Free radicals are typically formed by homolytic cleavage of covalent bonds, where each atom involved in the bond takes one of the shared electrons, resulting in the formation of two free radicals.
