OCT 2021 PBE Flashcards
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
a. the integrity of the benzene ring and the stable pi-bonding pattern remains intact
Electrophiles are
a. electron deficient species
b. electron rich species
c. electrically neutral species
d. positively charged ion
electron deficient species
SN2 means
a. two step nucleophilic substitution mechanism involving both alkyl halide and nucleophile
b. one step nucleophilic substitution mechanism involving both alkyl halide and nucleophile
c. two step nucleophilic substitution mechanism involving only the alkyl halide
d. one step nucleophilic substitution mechanism involving only the nucleophile
one step nucleophilic substitution mechanism involving both alkyl halide and nucleophile
In the decomposition and dissolution of solids during sample preparation, which of the following
is expensive and often the last resort?
a. Acid treatment using oxidation
b. Fusion technique
c. dissolution using ultrasound & appropriate solvent
d. Simple dissolution
Fusion technique
It is important to discard containers that are scratched or abraded on their interior surfaces. The
internal surface area of a container, whether used for sample preparation or storage, may cause
loss of
a. matrix
b. analyte
c. weight
d. ash
analyte
Glass container is not suitable for
a. inorganic trace analyses
b. oil and grease determination
c. microbiological analyses
d. all of the above
inorganic trace analyses
Which of the following is a primary standard for use in standardizing bases?
a. Ammonium hydroxide
b. Sulfuric acid
c. Acetic acid
d. Potassium hydrogen phthalate
d. Potassium hydrogen phthalate
A solution has been prepared by transferring 60 mL from Ortho-phosphoric acid 85 % (v/v)
H3PO4 and diluting it to 1.0 L, what is the concentration of the new solution.
a. 10.10%
b. 9.25%
c. 12.2%
d. 5.10%
5.10%
A student has got three stock standard solutions of 3 different elements, zinc (Zn) 2000 ppm,
cadmium (Cd) 1500 ppm and lead (Pb) 1000 ppm. A student took 10 mL from each solution and
transfers it to 200 mL volumetric flask then completed to total volume with solvent. What is the
final concentration of each element in the diluted mix solution?
a. 50 ppm Zinc, 32 ppm Cd, 25 ppm Pb
b. 100 ppm Zinc, 75 ppm Cd, 50 ppm Pb
c. 75 ppm Zinc, 75 ppm Cd, 50 ppm Pb
d. 100 ppm Zinc, 25 ppm Cd, 25 ppm Pb
b. 100 ppm Zinc, 75 ppm Cd, 50 ppm Pb
The HPLC column type in which molecules are separated according to size.
a. Ion exchange
b. size exclusion
c. normal phase
d. reverse phase
size exclusion
During ignition for ashing, muffle furnaces that go up to 1100oC are used primarily for this and
________ is needed to contain the sample.
a. porcelain crucible
b. evaporating dish
c. beaker
d. all of the above
a. porcelain crucible
A graphical representation of measuring signal as a function of quantity of analyte.
a. Calibration curve
b. Quality Control Chart
c. Absorbance Chart
d. None of the above
Calibration curve
n AAS method, If the sample concentration is too high to permit accurate analysis in linearity
response range, there are alternatives that may help bring the absorbance into the optimum
working range.
a. sample dilution
b. using an alternative wavelength having a lower absorptivity
c. reducing the path length by rotating the burner hand
d. All of the above
All of the above
A student has to measure out 9.40 mL of a liquid and selects a 100 mL graduated cylinder. To
improve the accuracy of the measurement, it would be most effective to:
a. take the average of multiple measurements using the graduated cylinder.
b. measure the liquid using a 25 mL graduated cylinder instead.
c. estimate the measurement obtained from the graduated cylinder to an additional significant
figure.
d. measure the liquid using a 10 mL graduated pipette instead.
measure the liquid using a 10 mL graduated pipette instead.
A buffer solution may be a mixture of
a. a weak acid and its salt
b. a weak base and its salt
c. an excess of a weak acid with a strong base
d. all of the above
d. all of the above
Which statement is true?
a. The value of the equilibrium constant increases with the addition of a catalyst
b. A catalyst speeds up both the forward and reverse reaction rates
c. The greater the activation energy, the faster the rate of reaction.
d. A catalyst increases the rate of reaction by decreasing the number of collisions
A catalyst speeds up both the forward and reverse reaction rates
What volume is occupied by 4.00 g of carbon dioxide, CO2 (44.0) gas at a pressure of 0.976 atm
and a temperature of 25.00C?
a. 0.191 L
b. 19.1 L
c. 2.28 L
d. 22.8 L
2.28 L
Molecular oxygen is highly soluble in the blood because
a. the hemoglobin molecule can bind up to four oxygen molecules
b. the solubility of oxygen is increased by the higher temperature of the body
c. pressure is increased inside the body
d. pressure inside the body is different outside of it
the hemoglobin molecule can bind up to four oxygen molecules
When water is heated in a beaker, bubbles of air form on the side of the glass before the water
boils. This shows that
a. the solubility of gases in water decreases with increasing temperature
b. the solubility of gases in water increases with increasing temperature
c. the solubility of gases in water decreases with decreasing temperature
d. the solubility of gases in water increases with decreasing temperature
a. the solubility of gases in water decreases with increasing temperature
The absorbance of different concentrations of potassium permanganate determined through UV
Vis Spectrophotometer is shown below.
Concentration, ppm Avg Absorbance
1.11 0.015
22.2 0.236
44.4 0.512
66.6 0.751
88.8 1.062
The Quality Control Sample for this run gave an average absorbance reading of 0.486. The theoretical concentration of the QC sample is 44.4 ppm. Calculate for the error of this QC run.
a. 0.0524
b. 0.0552
c. 0.0465
d. 0.00052
0.0524
Method of passing the sample through a metal or plastic mesh of a uniform cross-sectional area to
separate particles into uniform sizes.
a. sieving
b. pulverizing
c. macerating
d. milling
sieving
In handling acid wastes, what type of protective gloves should be used?
a. Cloth gloves
b. Surgical gloves
c. Rubber gloves
d. Disposal plastic gloves
Rubber gloves
What type of container must be used for acid or alkali wastes?
a. Polyethylene Drums
b. Metal drums
c. Fiber Drums
d. Cloth container
Polyethylene Drums
A solid waste management practice which refers to the controlled decomposition of organic
matter by microorganisms, mainly bacteria and fungi, into a humus-like product.
a. Composting
b. Recycling
c. Bioremediation
d. Reducing
Composting
A series of reference standards solutions that have known and accurate pH values at different
temperatures used for pH meter calibration.
a. Buffer Solutions
b. QC Solutions
c. pH solutions
d. None of the above.
Buffer Solutions
. Law that states the linear relationship between absorbance and concentration of an absorbing
species
a. Beer-Lambert’s Law
b. Charles Law
c. Boyles Law
d. Avogadro’s Law
Beer-Lambert’s Law
Type of quality-control sample used to evaluate the effects of sample matrices on the
performance of an analytical method
a. Matrix Duplicate
b. Matrix Spike
c. Method Blank
d. Reagent Blank
Matrix Spike
Component of error which, in the course of a number of analyses of the same measurand, remains
constant or varies in a predictable way.
a. Random Error
b. Analyst’s Error
c. Systematic Error
d. Uncertainty
Systematic Error
Determine the actual volume contained in a 50.0 mL volumetric flask given the following data:
Mass of water: 50.1227 g Density of water at 25˚ C : 0.99707 g/mL
a. 50.45 mL
b. 50.27 mL
c. 50.37 mL
d. 50.17 mL
50.27 mL
It is a pure dry solid substance of known chemical composition used in the direct standardization
of solution.
a. primary standard
b. secondary standard
c. analytical standard
d. indicator
primary standard
Sample preparation technique used prior to instrumental analysis of metals.
a. acid digestion
b. liquid-liquid extraction
c. sieving
d. clean-up
acid digestion
It is the closeness of the agreement between the result of a measured value and a true value.
a. Accuracy
b. Precision
c. Mean
d. Error
Accuracy
Which of the following chemicals may be used to neutralize waste containing caustic soda?
a. Potassium Hydroxide
b. Ammonia
c. Hydrochloric Acid
d. Buffer 10 Solution
Hydrochloric Acid
Which of the following are possible routes of exposure of the hazardous effect of waste?
a. Inhalation
b. Dermal
c. Ingestion
d. all of the above
all of the above
According to Revised DAO 04-36, the appropriate waste labels shall include:
a. Volume of Waste
b. Generator ID Number
c. Container Material
d. All of the above
All of the above
Sampling type that eliminates questions of bias in selection
a. composite
b. stratified
c. systematic
d. random
random
Reliability of the results decreases with a decrease in the level or concentration of the:
a. matrix
b. analyte
c. reactant
d. product
analyte
. Properties of nitric acid making it the preferred acid for digesting samples for the analysis of
metals.
a. acts as a strong acid
b. as an oxidizing agent
c. does not form insoluble compounds with metals/nonmetals
d. All of the above
All of the above
Possible sources of contamination during sample preparation include:
a. Reagents (tracers)
b. Glassware/equipment
c. Cross-contamination between high- and low-activity samples
d. All of the above
All of the above
The size of the sample taken for analysis depends on the concentration of the
a. analyte
b. equipment to be used
c. specific tests
d. All of the above
All of the above
Locating the adulterated portion of the lot for sampling is an example of
a. random sampling
b. selective sampling
c. composite sampling
d. stratified sampling
selective sampling
Quantitative chemical analysis of weighing a sample, usually of a separated and dried precipitate.
a. Titrimetric analysis
b. Volumetric analysis
c. Gravimetric analysis
d. Elemental analysis
Gravimetric analysis
The substance which does the dissolving and must be greater than 50% of the solution.
a. solvent
b. solute
c. mixture
d. solution
solvent
Requirements of a primary standard.
a. High Purity, 99.9% or better
b. Stability in air
c. Absence of hydrate water
d. All of the above
All of the above
Used for vacuum filtration using filter paper.
a. gooch crucible
b. Buchner funnel
c. rotary evaporator
d. rubber aspirator
Buchner funnel
. In chromatography, ________ is carried out on glass plates or strips of plastic or metal coated
on one side with a thin layer of adsorbent.
a. HPLC
b. GC
c. Paper Chromatography
d. Thin Layer Chromatography
Thin Layer Chromatography