1. Compared to freshwater, the same volume of natural seawater weighs:

A. 35% more
B. 3.5% more
C. 26% more
D. 2.6% more
E. 1.026% more
F. 1.020% more

2. The second most abundant ion in seawater is:

A. Sodium
B. Chloride
C. Magnesium
D. Sulfate
E. Calcium

3. The salinity of seawater can be determined by refractive index, which is the ratio of the speed of light traveling through the sample to the speed of light in vacuum. Some materials dissolved in water raise the refractive index, and some lower it. On balance, the ions in seawater:

A. Raise the refractive index compared to freshwater
B. Lower the refractive index compared to freshwater
C. Do not change the refractive index compared to freshwater

4.The form(s) of iodine in Lugol's solution are:

A. Iodide (I^-)₂
B. Molecular iodine (I₂)
C. Iodate (IO₃^-)
D. Organoiodine₂
E. Iodide and iodate₂
F. Iodide and molecular iodine₂
G. Iodate, iodide, and molecular iodine

5. Which of the following will not increase the TDS reading (as ppm TDS using a TDS meter) when put into freshwater at pH 7?

A. Sodium
B. Calcium
C. Ethanol (alcohol)
D. Nitrate
E. Acetic acid (vinegar)

6. Which of the following chemicals cannot raise ORP to any extent when added to a reef aquarium?

A. Ozone (O₃)
B. Ferrous sulfate (FeSO₄)
C. Bleach (hypochlorite; ClO^-)₂
D. Molecular Iodine (I₂)
E. Chlorine (Cl₂)
F. Bromine (Br₂)

7. When carbon dioxide dissolves into pure freshwater, the pH:

A. Drops
B. Rises
C. Remains the same

8. Sea urchin spines are composed primarily of:

A. Calcium sulfate
B. Magnesium carbonate
C. Potassium carbonate
D. Calcium carbonate
E. Sodium iodide

9. Which of the following is most toxic to typical marine fish?

A. 5 ppm nitrite
B. 2 ppm ammonia
C. 400 ppm potassium
D. 2,700 ppm sulfate
E. 7 ppm fluoride

10. Under which of the following conditions is an exposed coral skeleton most likely to begin to dissolve (all other conditions equal natural seawater)?

A. Calcium 210 ppm, alkalinity 2.5 meq/L (7.0 dKH), pH 8.2
B. Calcium 420 ppm, alkalinity 1.0 meq/L (4.2 dKH), pH 8.2
C. Calcium 210 ppm, alkalinity 1.5 meq/L (4.2 dKH), pH 8.5
D. Calcium 300 ppm, alkalinity 2.0 meq/L (5.6 dKH), pH 8.2
E. Calcium 500 ppm, alkalinity 3.0 meq/L (8.4 dKH), pH 8.2
F. Calcium 420 ppm, alkalinity 2.0 meq/L (5.6 dKH), pH 7.6

11. When measuring seawater's salinity via conductivity, which of the following must be taken into account if the salinity is to be accurate to within 4%?

A. Calcium unusually high at 550 ppm
B. Phosphate unusually high at 1 ppm
C. Alkalinity unusually low at 1 meq/L (2.8 dKH)
D. Temperature within 5 degrees of the standard temperature for such measurements (25°C)
E. Calcium unsually low at 250 ppm
F. None of the above

12. Which of the following actions will most likely permit adjustment of an aquarium with a calcium concentration of 320 ppm and an alkalinity of 2.5 meq/L (7 dKH) to match natural seawater with a calcium concentration of 420 ppm and an alkalinity of 2.5 meq/L (7 dKH)?

A. Adjusting a calcium carbonate/carbon dioxide reactor to add more CO₂, increasing its output.
B. Adding limewater for a week, replacing all evaporated water.
C. Adding a solution of baking soda over three days.
D. Adding a solution of calcium chloride all at once.
E. Adding a solution of baked baking soda (baked at 300°F for one hour before dissolving).

13. Which form of calcium carbonate dissolves first in seawater as the pH is steadily lowered from 8.2?

A. Calcite
B. Aragonite
C. Struvite
D. Gypsum

14. Approximately what percentage of the buffering of natural seawater is provided by boric acid/borate at pH 8.2?

A. 0.25%
B. 1.5%
C. 13%
D. 23%
E. 78%

15. The radular teeth of mollusks can contain substantial amounts of:

A. Silicon and iron
B. Potassium and cobalt
C. Boron and sulfate
D. Sodium and chloride
E. Zinc and bromide

16. What is the conversion between different units of total alkalinity?

A. 1 meq/L = 2.5 dKH = 250 ppm CaCO₃ equivalents
B. 1 meq/L = 7 dKH = 200 ppm CaCO₃ equivalents
C. 1 meq/L = 11 dKH = 200 ppm CaCO₃ equivalents
D. 1 meq/L = 2.8 dKH = 50 ppm CaCO₃ equivalents

17. Total alkalinity is a measure of the amount of acid required to convert all of the bicarbonate and carbonate to carbonic acid. In natural seawater, that is accomplished by adding acid until the pH is approximately:

A. 6.2
B. 5.5
C. 4.2
D. 2.7
E. 1.8

18. Which equation best describes total alkalinity (TA) in natural seawater (the bracket symbol means the concentration of the ion inside it)?

A.  TA = [HCO₃^-] + 2[CO₃^--] + [B(OH)4^-] + [OH^-] + [Si(OH)₃O^-] + [MgOH⁺] + [HPO₄^--] + 2[PO₄^---] - [H⁺]

B.  TA = [HCO₃^-] + [CO₃^--] + [B(OH)4^-] + [OH^-] + [Si(OH)₃O^-] + [MgOH⁺] + [HPO₄^--] + 2[PO₄^---] - [H⁺]

C.  TA = [HCO₃^-] + 2[CO₃^--] + [B(OH)4^-] + [OH^-] + 3[Si(OH)₃O^-] + [MgOH⁺] + [HPO₄^--] + 2[PO₄^---] - [H⁺]

D. TA = [HCO₃^-] + [CO₃^--] + [B(OH)4^-] + [OH^-] + [Si(OH)₃O^-] + [MgOH⁺] + 2[HPO₄^--] + 3[PO₄^---] - [H⁺]

19. The predominant form of inorganic iodine in surface seawater is:

A. Iodide (I^-)₂
B. Iodate (IO₃^-)
C. Molecular Iodine (I₂)
D. Organoiodine_.
E. None of the above

20. The approximate concentration of strontium in natural seawater at 35 ppt salinity is:

A. 4 ppm
B. 8 ppm
C. 12 ppm
D. 40 ppm

21. Granular ferric oxide (GFO; ferric oxide hydroxide; the iron based phosphate binders) might be expected to usefully reduce all of the following in a reef aquarium except:

A. Nitrate
B. Phosphate
C. Organics
D. Hydrogen sulfide
E. Silicate

22. Which of the following would be expected to most readily pass through a reverse osmosis membrane?

A. Sodium and chloride
B. Magnesium and sulfate
C. Carbon dioxide and hydrogen sulfide
D. Proteins and carbohydrates
E. Bacteria and viruses

23. When adding a high pH additive (such as the alkalinity part of a two-part additive, or limewater) to reef aquarium water, a transient cloudiness forms.

This cloudiness is primarily:

A. Calcium carbonate
B. Calcium hydroxide
C. Magnesium carbonate
D. Magnesium hydroxide
E. Magnesium oxide

24. Boron is present in seawater at pH 8.2 in which of the following forms?

A. 70% Boric acid (B(OH)₃), 30% boride (B^-)_.
B. 70% Boric acid (B(OH)₃), 30% borate (B(OH)₄^-)
C. 30% Boric acid (B(OH)₃), 70% borate (B(OH)₄^-)
D. 30% Boric acid (B(OH)₃), 70% boride (B^-)

25. Balanced two-part calcium and alkalinity additive systems consist of two separate additives, one of which supplies calcium and the other of which supplies alkalinity. Once the calcium and alkalinity are removed by corals in the aquarium, these systems necessarily leave behind extra ions. These systems are often designed so that these extra ions are in the same ratio that they are present in seawater. In order to accomplish this requirement, which two ions, aside from calcium and carbonate/bicarbonate, must be the two most abundant ions in each part of it?

A. Sodium in the alkalinity part and magnesium in the calcium part
B. Sodium in the alkalinity part and chloride in the calcium part
C. Sodium in the alkalinity part and sulfate in the calcium part
D. Chloride in the alkalinity part and magnesium in the calcium part
E. Chloride in the alkalinity part and sodium in the calcium part
F. Chloride in the alkalinity part and sulfate in the calcium part

26. Strontium in seawater is most similar chemically to which of the following other ions in seawater?

A. Sodium
B. Lithium
C. Chloride
D. Calcium
E. Iron
F. Aluminum

27. In seawater at pH 8.2, which form of inorganic phosphate predominates?

A.  H₃PO₄
B.  H₂PO₄^-
C.  HPO₄^--
D.  PO₄^---

28. Which of the following ions is predominately bound to organics when dissolved in seawater?

A. Calcium
B. Magnesium
C. Bromide
D. Fluoride
E. Copper

29. Activated carbon would be a good way to remove which of the following from a reef aquarium?

A. Excess magnesium
B. Excess calcium
C. Excess bromide
D. Organic toxins

30. Imagine a 100-gallon reef aquarium with water parameters of 320 ppm calcium, 2.5 meq/L (7 dKH) alkalinity, and a pH of 8.2. What would be the best way to bring move this aquarium toward natural seawater's values for these parameters?

This calculator may help:
http://home.comcast.net/~jdieck1/chem_calc3.html

A. Add 105 grams (~21 teaspoons) of anhydrous calcium chloride dissolved into freshwater and add to a high flow area away from organisms.
B. Add 12 gallons of saturated limewater over the course of a week or so, dripped slowly.
C. Increase the CO2 addition rate on the existing calcium carbonate/carbon dioxide reactor so that calcium slowly rises over the course of a week or so, then reduce the addition rate until it stabilizes at the desired calcium level.
D. Add 139 grams (~28 teaspoons) of Dowflake calcium chloride dissolved into freshwater and add to a high flow area away from organisms, along with 115 grams (~25 teaspoons) of baking soda dissolved into freshwater and add to a high flow area away from organisms.

31. If the water clarity is uniform, and 50% of the intensity of a particular wavelength of yellow light penetrates to a depth of 15 feet on a coral reef, what percentage of the original intensity penetrates to 45 feet?

A. 50%
B. 25%
C. 15%
D. 12.5%

32. Why do some aquarists bake baking soda in a kitchen oven at 300° F for one hour prior to use?

A. The baking releases water so that the remaining solid is more potent at boosting calcium in the aquarium.
B. The baking releases carbon dioxide so that it raises both pH and alkalinity in the aquarium.
C. The baking releases carbon dioxide so that it raises pH without raising alkalinity.
D. The baking releases water so that it has a pH lowering effect on the aquarium.
E. The baking converts sodium carbonate into sodium bicarbonate, which then allows it to boost alkalinity in the aquarium.

33. Which of the following is a nitrite ion?

A. N^-_.
B. NO^-_.
C. NO₂^-
D. NO₃^-
E. NO₄^-

34. The pH of saturated limewater (calcium hydroxide or calcium oxide dissolved in freshwater, also known as kalkwasser in German) at 25° C (77° F) is closest to:

A. 8.25
B. 9.2
C. 12.15
D. 12.45

35. The pH buffering capacity is an indication of the ability of a water sample to resist changes in pH when small amounts of acid or base are added. In which of these solutions is the buffering capacity the highest?

A. Natural seawater at pH 7.7
B. Natural seawater at pH 8.0
C. Natural seawater at pH 8.2
D. Natural seawater at pH 8.4

36. If a reef aquarium has the following parameters: 420 ppm calcium, 3 meq/L (8.4 dKH) alkalinity, pH 8.7, which of the following is the least suitable way to reduce the pH:

A. Add soda water (seltzer)
B. Add vinegar
C. Add baked baking soda
D. Increase aeration

37. In an established reef aquarium being supplemented with limewater (kalkwasser), aquarists sometimes find that over a period of a few days, alkalinity drops more than calcium. For example, alkalinity drops by 33% from 3 meq/L to 2 meq/L while calcium drops by less than 5% from 440 ppm to 420 ppm. What is the primary cause of that difference?

A. Limewater does not add alkalinity, only calcium.
B. Limewater is not a balanced additive.
C. Seawater contains a lot more calcium than alkalinity.
D. Seawater contains a lot more alkalinity than calcium.

38. The conductivity of natural seawater is closest to:

A. 53 mS/cm
B. 35 mS/cm
C. 1.025 mS/cm
D. 3.5 mS/cm

39. If an aquarist wanted to produce a hyposaline solution with a specific gravity of about 1.009, that can be best accomplished by mixing which of the following solutions?

A. Mixing 90% pure fresh water with 10% seawater (sg = 1.0264)
B. Mixing 66% pure fresh water with 34% seawater (sg = 1.0264)
C. Mixing 33% pure fresh water with 67% seawater (sg = 1.0264)
D. Mixing 13% pure fresh water with 87% seawater (sg = 1.0264)

40. Which of the following is necessarily true in seawater starting at pH 8.2?

A. As the pH declines, the concentration of hydroxide declines.
B. As the pH rises, the concentration of hydroxide declines.
C. As the pH rises, the concentration of calcium rises.
D. As the pH declines, the alkalinity rises.

41. Halides are a family of ions that are very important, both in seawater and in metal halide lamps. Which of the following is not a halide?

A. Fluoride
B. Chloride
C. Bromide
D. Iodide
E. Actinide

42. If you have a floating glass hydrometer in a marine aquarium, the specific gravity is read by matching the height that it floats in the water to a built-in scale on its side. If the water sample is allowed to cool, the hydrometer will:

A. Rise higher in the water, indicating a lower number.
B. Sink lower into the water, indicating a higher number.
C. Rise higher in the water, indicating a higher number.
D. Sink lower in the water, indicating a lower number.

43. Why can't you add magnesium chloride to limewater (kalkwasser) to get a supplement that adds calcium, alkalinity and magnesium?

A. The calcium will precipitate as calcium chloride.
B. The magnesium will suppress the calcium solubility, leaving much less calcium in solution.
C. The chloride will clog the drip tip.
D. The magnesium will precipitate as magnesium hydroxide.

44. Which statement about dissolved organic molecules in the ocean is true?

A. Certain classes of dissolved organic molecules have been shown to circulate in the ocean largely unchanged for thousands of years.
B. The surface ocean concentration of dissolved organic molecules is typically about 20-30 ppm.
C. The nature of organic molecules in the ocean is well understood.
D. The ratio of carbon to phosphorus to nitrogen in dissolved organic molecules is roughly 100:5:1.

45. Chloramine is sometimes added to municipal water treatments to kill pathogens in tap water. Which of the following is not a suitable way to remove chloramine before using it in a reef aquarium?

A. Pass it though activated carbon, then through a deionizing resin.
B. Pass it though activated carbon, then a reverse osmosis membrane, then through a deionizing resin.
C. Treat the water with hydroxymethanesulfonate, the active ingredient in Amquel and ClorAm-X.
D. Allow the tap water to sit for 24-48 hours before use.

46. Which of the following has not been shown to limit the growth of phytoplankton and macroalgae in any part of the ocean?

A. Strontium
B. Light
C. Iron
D. Nitrogen
E. Phosphorus

47. Which of the following does not increase the solubility of calcium carbonate in seawater?

A. Reducing the pH with carbon dioxide
B. Reducing the pH with hydrochloric acid
C. Increasing the pressure
D. Decreasing the pressure

48. A stock solution is made by dissolving 8.401 grams of baking soda (sodium bicarbonate; molecular weight = 84.01 g/mole) into enough pure freshwater at 25° C to make 1 L total volume. This solution has a pH of 8.300 and an alkalinity of 100.00 meq/L (~280 dKH). 1.000 mL of this solution is added to 99.000 mL of natural seawater (pH 8.200; 2.500 meq/L). The alkalinity of the final solution is closest to:

A. 3.500 meq/L
B. 3.475 meq/L
C. 2.515 meq/L
D. 2.500 meq/L

49. The same mixture is made as in question 48. The pH of the final solution (before gas exchange with the air) is:

A. Exactly 8.200
B. Exactly 8.201
C. Above 8.201
D. Below 8.200

50. The same mixture is made as in question 48. The pH of the final solution after complete equilibrium of all gases with normal air is:

A. Exactly 8.200
B. Exactly 8.201
C. Above 8.201
D. Below 8.200

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