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CWEA GRADE 1 LAB ANALYST PRACTICE TEST 2 QUESTIONS WITH CORRECT ANSWERS, Exams of Water Resources Planning and Management

California Institute of Technology (Caltech)Water Resources Planning and Management

CWEA GRADE 1 LAB ANALYST PRACTICE TEST 2 QUESTIONS WITH CORRECT ANSWERS

Typology: Exams

2024/2025

Available from 07/13/2025

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CWEA GRADE 1 LAB ANALYST PRACTICE TEST 2
QUESTIONS WITH CORRECT ANSWERS
1) What is chloride? -- Answer ✔✔ Major anion found in many natural waters - Can
impart salty taste in H2O
2) What increases the concentration of chloride in wastewater? -- Answer ✔✔
Chloride in human diet and softeners flushed into sanitary sewer system
3) 2 most prevalent methods of measuring chloride? -- Answer ✔✔ argentometric and
mercuric nitrate
4) What is the Argentometric method? -- Answer ✔✔ Titration of the sample with a
standard solution of silver nitrate (AgNO3) - Indicator: Chromate ions (CrO4) - End
point: reddish silver chromate
5) What is the Mercuric Nitrate method? -- Answer ✔✔ Titration with standard
mercuric nitrate solution -pH must be adjusted between 2.3 and 2.8 - Indicator:
Diphenyl carbazone - End point: Change from blue to purple in the presence of
mercury
pf3
pf4
pf5

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CWEA GRADE 1 LAB ANALYST PRACTICE TEST 2

QUESTIONS WITH CORRECT ANSWERS

  1. What is chloride? -- Answer ✔✔ Major anion found in many natural waters - Can impart salty taste in H2O
  2. What increases the concentration of chloride in wastewater? -- Answer ✔✔ Chloride in human diet and softeners flushed into sanitary sewer system
  3. 2 most prevalent methods of measuring chloride? -- Answer ✔✔ argentometric and mercuric nitrate
  4. What is the Argentometric method? -- Answer ✔✔ Titration of the sample with a standard solution of silver nitrate (AgNO3) - Indicator: Chromate ions (CrO4) - End point: reddish silver chromate
  5. What is the Mercuric Nitrate method? -- Answer ✔✔ Titration with standard mercuric nitrate solution - pH must be adjusted between 2.3 and 2.8 - Indicator: Diphenyl carbazone - End point: Change from blue to purple in the presence of mercury
  1. Which of the following can be an Interference of the Mercuric Nitrate Method? -- Answer ✔✔ Sulfide, bromide, orthophosphate (over 30 ppm), and iodide
  2. Why does the color change in water? a. Presence of decaying vegetable matter b. metal ions (ie. iron) c. industrial and domestic pollution d. All of the above -- Answer ✔✔ d
  3. How is color measured -- Answer ✔✔ Measured using visual comparison method
  4. What is the visual comparison method -- Answer ✔✔ Sample compared to standards using matching nessler tubes - Standards prepared with solution containing chloroplatinate and cobaltous chlorid
  5. What is the standard unit for color? -- Answer ✔✔ One unit= color resulting from 1 mg of platinum/L
  6. What is 2-color reporting? -- Answer ✔✔ True and Apparent
  7. Define True color -- Answer ✔✔ Color from suspended solids, determine using sample treated to remove turbidity
  8. What is Apparent Color? -- Answer ✔✔ Color from both dissolved and suspended solids
  1. What is the primary reason for measuring alkalinity? -- Answer ✔✔ Used in control of many water and wastewater unit processes
  2. How is alkalinity measured? -- Answer ✔✔ Titration of a sample with a standard solution of either sulfuric acid or hydrochloric acid to predetermined pH endpoint
  3. The phenolphthalein alkalinity of a water sample is zero if: -- Answer ✔✔ The pH is greater than 8.
  4. What is Atomic Weight? -- Answer ✔✔ the number of protons plus the number of neutrons
  5. What is a Base? -- Answer ✔✔ A compound that liberates hydroxide ions and has a pH above 7.
  6. Define Biochemical Oxygen Demand (BOD)? -- Answer ✔✔ The quantity of oxygen utilized in the biochemical oxidation of organic matter under standard laboratory procedures for five days at 20° Centigrade, usually expressed as a concentration (e.g., mg/L). BOD measurements are used to indicate the organic "strength" of wastewater.
  7. What is a Chain-of-Custody? -- Answer ✔✔ A legal record (which may be a series of records) of each person who had possession of an environmental sample, from the person releasing the sample to the person who collected the sample, to the person who analyzed the sample in the laboratory, to the person who witnessed the disposal of the sample.
  1. What is Chemical Oxygen Demand (COD)? -- Answer ✔✔ The amount of oxygen (expressed in mg/L) consumed from the oxidation of pollutants during a specific test. As such, COD is a measure of the oxygen-consuming capacity of the pollutants present in wastewater. The results of the COD test are not necessarily related to the BOD, because the chemical oxidant responsible for utilizing the oxygen may react with substances that bacteria do not stabilize.
  2. What is a Composite Sample? -- Answer ✔✔ A collection of individual samples obtained at regular intervals, based either on flow or time. The individual samples are combined proportionally.
  3. If you have been given instructions you don't understand? -- Answer ✔✔ Ask the author/supervisor
  4. Why is the Mercuric nitrate titration technique for measuring chloride falling into disuse in the lab? -- Answer ✔✔ Mercury creates a hazardous waste problem
  5. Why should standard phenyl arsine oxide solution be handled with caution? -- Answer ✔✔ Because it is a severe poison
  6. The sampling protocol for chloride includes: -- Answer ✔✔ Glass or plastic container with no preservative
  7. What is the incubator temperature for BOD? -- Answer ✔✔ 20 +/- 1 degrees C
  8. How can laboratory mistakes be corrected? -- Answer ✔✔ Lining out the mistake with pen and writing the correct answer to the side of the first, with the analyst's initials and date
  1. pH measurement requires the following: -- Answer ✔✔ voltmeter, glass pH electrode, reference electrode, and a temperature compensating device
  2. Conductance measurements are temperature compensated to: -- Answer ✔✔ 25 degrees C
  3. The conductivity meter is calibrated with: -- Answer ✔✔ 0.0100 N potassium chloride standard
  4. What is Alkalinity reported as? -- Answer ✔✔ Alkalinity mg CaCO3/L