* not completed

. Which of the following statements regarding complexes of metal ions is/are true? (Please select all that apply)

Deprotonation of aquo complexes occurs more readily for highly charged metal ions compared to ions with smaller charge correct incorrect

Deprotonation of aquo complexes occurs more readily for larger metal ions correct incorrect

The loss of the first proton occurs more readily than for the second one correct incorrect

In solutions having pH greater than the pK₁ for an aquo complex, the existing aquo complex will have a negative charge correct incorrect

Some metal ions exist as neutral aquo complexes in solution correct incorrect

* not completed

. Which factor(s) can affect the nature of complexes formed by aluminium in water? (Please select all that apply)

pH correct incorrect

ionic strength correct incorrect

presence of organic matter            correct incorrect

pE correct incorrect

Temperature correct incorrect

* not completed

. Which of the following statements about environmental properties of elements is/are true? (Please select all that apply)

Most Type B elements are micronutrients correct incorrect

Borderline elements tend to form methylated compounds correct incorrect

Several Type A elements are macronutrients for living organisms correct incorrect

Type B elements usually form strong complexes with sulfur-containing ligands correct incorrect

There is generally a direct correlation between electronegativity of the coordinating atom in the ligand and stability of complexes formed with type B metal ions. correct incorrect

* not completed

. Which of the following statements about environmental properties of elements is/are true? (Please select all that apply)

Many micronutrients for aquatic organisms are transition metals correct incorrect

Ligands having coordinating atoms with low electronegativity tend to form weaker complexes with Type B metals than those with atoms of high electronegativity correct incorrect

Some Type A metals are essential nutrients for aquatic organisms correct incorrect

Iron oxides in oxygen-limited sediments are highly insoluble correct incorrect

Gold and mercury are closely associated in minerals in the river sediments of the Amazon basin correct incorrect

* not completed

. Which of the following statements about environmental properties of elements is/are true?  (Please select all that apply)

Type A metals rarely form aquo complexes correct incorrect

Both oxidizing and reducing mechanisms describing the solubilisation of mineral bound arsenic species have been postulated correct incorrect

Manganese oxide minerals can become soluble under reducing conditions in water correct incorrect

Mercury(II) chloro complexes can volatilize from water correct incorrect

In estuarine environments, sodium ion can displace and make soluble sediment-bound metals correct incorrect

* not completed

. Which of the following statements about ligands of anthropogenic origin is/are true? (Please select all that apply)

Ammonia is a degradation product of organic waste correct incorrect

Sulfide and other forms of sulfur are usually derived from the pharmaceutical industry correct incorrect

Phosphate is mostly derived from industrial wastewater correct incorrect

Cyanide is a product of the mining industry correct incorrect

EDTA is used as an industrial cleaner correct incorrect

* not completed

. Which of the following statements about bioavailability of metals is/are true? (Please select all that apply)

The first step in uptake of a metal by an organism is binding of the metal to the cell wall correct incorrect

Toxicity is generally related to the concentration of the complexed, potentially toxic metal in water correct incorrect

Toxicity involves the metal moving into the cells of the organism correct incorrect

Uptake of metals by fish is usually related to the free metal concentration in solution correct incorrect

The BLM would predict that NTA inhibits the uptake of metals by organisms correct incorrect

* not completed

. Which of the following statements about metals in water is/are true? (Please select all that apply)

Mg²⁺ is likely to form only weak complexes with humic material correct incorrect

Fe³⁺ in water containing dissolved  humic material is likely to be substantially complexed with the organic matter correct incorrect

Al³⁺, a Type A metal is not likely to form complexes with organic matter in water correct incorrect

When Hg²⁺ is converted to methylated forms, its volatility is reduced correct incorrect

The stability of Pb²⁺ with organic ligands can be explained by an electrostatic model correct incorrect

* not completed

. Which of the following statements about mercury is/are true? (Please select all that apply)

Mercury(II) chloro species are soluble in water correct incorrect

Organic matter in sediments favours methylation of elemental mercury correct incorrect

Volatile Hg⁰ is rained out from the atmosphere after it has been oxidized to Hg²⁺ correct incorrect

Methylated mercury can be ingested by carnivores correct incorrect

Volatile (CH₃)₂Hg is rained out from the atmosphere after the mercury has been oxidized to Hg²⁺ correct incorrect

* not completed

. Consider a solution containing 35 ppb Zn²⁺ at pH 5.0, with fulvic acid (FA) present, assuming a concentration of binding sites equal to 4.0x10^-5 mol L^-1. Which of the following is/are true? (Please select all that apply)

Zinc ions do not bind with fulvic acid correct incorrect

86% of the Zn²⁺ is complexed with FA correct incorrect

14% of the Zn²⁺ is complexed with FA correct incorrect

4.6x10^-7 mol L^-1 Zn²⁺ is uncomplexed correct incorrect

7.4x10^-8 mol L^-1 ZnFA complex is present at equilibrium correct incorrect