Practice Test Geeks(CWS) Certified Water Specialist Practice Test
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Water Chemistry & Contaminant Identification Flashcards

7 cards from real CWS practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

Read the first 7 Water Chemistry & Contaminant Identification flashcards as text

  1. Perchlorate contamination in drinking water is most commonly associated with:

    Answer: Agricultural fertilizers and rocket fuel manufacturing

    Perchlorate originates primarily from rocket fuel, explosives manufacturing, and certain fertilizers containing Chilean nitrate.

  2. When testing for free chlorine residual using DPD (N,N-diethyl-p-phenylenediamine), the resulting color is:

    Answer: Pink-red

    Free chlorine reacts with DPD reagent to produce a pink-red color whose intensity is proportional to chlorine concentration.

  3. Which of the following best describes the difference between primary and secondary drinking water standards?

    Answer: Primary standards protect health; secondary standards address aesthetic qualities

    Primary MCLs are enforceable health-based limits, while secondary standards are non-enforceable guidelines for aesthetic qualities like taste, odor, and color.

  4. A water sample with high conductivity most likely contains:

    Answer: Elevated dissolved salts and minerals

    Electrical conductivity in water increases proportionally with dissolved ion concentration, indicating elevated salts and minerals.

  5. Calcium hypochlorite (Ca(OCl)₂) when dissolved in water produces which primary disinfecting species?

    Answer: Hypochlorous acid (HOCl) and hypochlorite ion (OCl⁻)

    Calcium hypochlorite hydrolyzes in water to form hypochlorous acid and hypochlorite ions, which are the active disinfecting species.

  6. PFAS (per- and polyfluoroalkyl substances) in drinking water are most challenging to remove because they:

    Answer: Have extremely strong carbon-fluorine bonds making them chemically persistent

    PFAS are called 'forever chemicals' because carbon-fluorine bonds are among the strongest in chemistry, resisting degradation by conventional treatment methods.

  7. Which condition in a water distribution system most promotes the growth of iron bacteria (Gallionella, Leptothrix)?

    Answer: Presence of soluble iron and low dissolved oxygen

    Iron bacteria thrive in environments with soluble ferrous iron as an energy source and low dissolved oxygen conditions.