Practice Final – December, 2006

1. The oxidation state of sulfur (S) in SO 4 2- is: (a) +6 (b) +4 (c) +2 (d) 0 2. If there is no disinfectant in the distribution system of the drinking water supply, recontamination can occur due to: (a) low pressure at the outer edges of the distribution system, allowing contamination from the ground. b) formation of chloroform and other chlorinated compounds (c) loss of ozone in the distribution system (d) none of the above (a) low pressure at the outer edges of the distribution system, allowing contamination from the ground.

3. When using incineration to reduce waste, one of the disadvantages is (a) impossible to recover trace metals from the fly ash (b) inability to recover waste heat (c) formation of polychorinated dibenzo-p-dioxins and dibenzofurans (d) low efficiency in the destruction of hazardous materials (c) formation of polychorinated dibenzo-p-dioxins and dibenzofurans 4. Chlorinated solvents are the subject of environmental concern because of (a) their ozone depletion potential (b) their potential to chelate other compounds (c) their potential to form other compounds (d) none of the above (a) their ozone depletion potential

5. When considering the toxicity of trace metals the most important factor effecting the the metal's toxicity is its: ( a) speciation (b) absorption spectrum (c) atomic weight (d) density (a) speciation 6. Which of the following statements is true regarding methymercury in fish. (a) Methylmercury in fish is found only in the digestive tract. (b) Fish cannot bioaccumlate mercury. (c) Highest concentrations found in long-lived predatory fish. (d) once the fish has consumed the methymercury, there is no process for elimination. (c) Highest concentrations found in long-lived predatory fish

7. Most of the mercury present in humans is in the form of (a) Hg o (b) Hg 2 2+ (c) Hg 2+ (d) methylmercury (d) methylmercury Given the dissociation constant for acetic acid; 1.8 x (a) Calculate the pH for a 0.04 M solution of acetic acid, HOAc. HOAc  H + + Oac - K a = 1.8x x x x [x][x]/0.04 = 1.8x10 -5 [x] 2 = 7.2 x10 -7 [x] = 8.48x10 -4 pH = 3.07

(b) What would be the pH if 0.01 M NaOAc were added to the solution. HOAc  H + + OAc - K a = 1.8x x x x [x][0.01]/[0.04] = 1.8 x x = 7.2 x pH = 4.14

13. The two figures show the dose-response curves for exposure of two organisms to a specific toxicant. (a) both curves have the same EC 50 values (b) both organisms have the same LOEC (lowest observed effective conc.) (c) there is no correlation between the two graphs (d) all the organisms have the same susceptibility to the chemical toxicant (a) both curves have the same EC 50 values

14. Which of the following statements is not true? (a) underlying limestone rocks can provide a buffering system to mitigate the effects of acid rain. (b) in early spring there is often an influx of the winter's accumulation of acid snow. (c) trees at high altitudes are least affected by acid rain due to protection of low-lying clouds. (d) "sulfation" is the replacement of CaCO 3 by CaSO 4 on historical monuments. (c) trees at high altitudes are least affected by acid rain due to protection of low-lying clouds Given K H (Henry's law constant) = 3.38x10 -2 moles L -1 atm -1 and K a1 = 4.45x10 -7 for carbonic acid (H 2 CO 3 ), calculate the pH of water in equilibrium with CO 2 in the atmosphere where the concentration of [CO 2 ] = 316 ppm. [H 2 CO 3 ] = 3.16x10 -4 x 3.38 x10 -2 [H 2 CO 3 ] = 1.06 x H 2 CO 3  H + + HCO x x x x [x}{x] = 4.7x [x] = 2.1x10 -6 pH = 5.68

18. Which one of the following ions is responsible for making water "hard"? a. Na + b. Mg 2+ c. SO 4 2- d. CO 3 2- b. Mg 2+

21. The difference between the effect of DDT and DDE on the calcification of eggshells is due to (a) number of chlorine atoms (b) structure (c) chemical reactivity (d) lipophilicity (b) structure 22. The octanol-water partition coefficient measures (a) ease of reduction (b) half-life (c) chlorine/hydrogen ratio (d) degree of lipophilicity (d) degree of lipophilicity 23.When studying the eggs of migratory birds for DDT and DDE a high ratio of DDT to DDE means (a) the birds have encountered a place where DDT is still likely being used (b) the egg shells will be too thin to allow hatching (c) organophosphorus pesticides are replacing the chlorinated pesticides (d) the migratory birds will tend to not migrate any longer (a) the birds have encountered a place where DDT is still likely being used

24. When considering the environmental fate of a molecule, one must consider (a) temperature (b) pH of the environment (c) microorganisms (d) all of these (d) all of these 25. The figure on the left shows the H 2 CO 3, HCO 3 -, CO 3 2- fractions in natural water as functions of pH. The line B represents: (a) H 2 CO 3 (b) HCO 3 - (c) CO 3 2- (d) H 2 O b) HCO 3 -

PCBs (a) can form dioxins when heated (b) have been shown to cause IQ deficiency when content in blood is high (c) have the same toxicity, regardless of the congener (d) are disposed of by electrolysis b) have been shown to cause IQ deficiency when content in blood is high 27.Petroleum Aromatic Hydrocarbons (PAHs) are (a) pollutants associated with incomplete combustion (b) are volatile organic hydrocarbons (c) known to react with air to form furans (d) none of these (a) pollutants associated with incomplete combustion 28. Dissolved oxygen in water can be effected by (a) decomposition of biomass (b) thermal pollution (c) sewage (d) all of these (d) all of these

29. CH 3 Hg + and (CH 3 ) 2 Hg are (a) both present in the atmosphere as gaeous molecules. (b) both lipid soluble (and hence bioconcentrate) (c) both kinetically reactive, and thus very unstable. (d) all of the above. (b) both lipid soluble (and hence bioconcentrate) 30. The principal risk to children from lead is (a) skin cancer (b) damage to the retina (c) “blue baby” syndrome (d) interference with development of the brain. (d) interference with development of the brain.

Questions relate to this figure which shows the biological response of organisms to toxicant concentrations 31.Region C represents (a) no toxic effect(b) irreversible effects (b) death(d) none of these (b) irreversible effects 32.A micronutrient, e.g. copper, is represented by (a) curve 1 (b) curve 2 (c) curves 1 and 2 (d) neither curve 1 or 2 (a) curve 1 33.Acute toxicity testing occurs in (a) Region A (b) Region B (c) Region C (d) Region D (d) Region D

34. In the use of hypochlorous acid, HOCl as a disinfectant, the pH is maintained around 7.5 to: (a) increase the solubility of Cl 2 gas (b) prevent the ionization of HOCl to hypochlorite ion, OCl - HOCl(aq) H + (aq) + OCl - aq) (c) make the water taste better. (d) keep phosphates from precipitating out. (b) prevent the ionization of HOCl to hypochlorite ion, OCl - HOCl(aq) H + (aq) + OCl - aq) 35. Which of the following is not a disinfectant in the treatment of drinking water (a) ClO 2 (b) H 2 O 2 (c) UV light(d) O 3 (b) H 2 O Which of the following compounds is a xenobiotic substance? (a) N 2 O (b) CO 2 (c) CHCl 3 (d) O 3 (c) CHCl 3

37. The trace greenhouse gases: methane, nitrous oxide, and CFCs will likely have a combined effect comparable to CO 2 because of (a) their absolute levels of emission (b) their efficiency of radiation trapping (c) their atmospheric lifetime (d) all of these. (d) all of these 38. Which of the following species absorbs infrared radiation in the troposphere? a. N 2 b. O 2 c. CO 2 d. Ar c. CO 2

40. Which of the following reactions is representative of hydroxyl free radical chemistry? (a) CHCl 3 + OH > CHCl 2 OH + Cl (b) CHCl 3 + OH > CHCl 2 + HCl (c) OH(g) + NO 2 (g) M-----> HNO 3 (g) (d) CHCl 3 + OH > CH 2 OCl + Cl 2 (c) OH(g) + NO 2 (g) M-----> HNO 3 (g) 41. Which of the following reactions is not necessary in the major route for the formation of the hydroxyl radical in the troposphere? (a)NO h, NO + O (b)O 2 + NO > NO + O 3 (c) O h, O 2 * + O* (d)O* + H 2 O > 2 OH (where O* is an excited oxygen atom) (b)O 2 + NO > NO + O 3

42. The most common fate of peroxy radicals in tropospheric air, except of the very cleanest of air as that over the ocean, is illustrated in which of the following reactions: (a) HSO 3 + NO >NO 2 +HSO 2 (b) H 2 O >H 2 + O 2 (c) CH 3 COO + OH > CH 3 COH + O 2 (d) HSO 2 + OH >H 2 SO 3 (a) HSO 3 + NO >NO 2 +HSO Which of the following reactions takes place in a catalytic converter (a) OH + SO > HSO 3 (b) CO 2 +1/2 N > CO+ NO (c) H 2 + NOx >N 2 + H 2 O (d) 1/2 O 2 + NO > NO 2 (c) H 2 + NOx >N 2 + H 2 O

Given the following equilibria constants H 2 CO > H + + HCO 3 - Ka1 = 4.5 x HCO > H + + CO 3 2- Ka2 = 4.7 x CaCO > Ca 2+ + CO 3 2- Ksp = 4.6 x calculate the equilibrium constant for the reaction HCO H 2 O > H 2 CO 3 + OH - K = [H 2 CO 3 ][OH - ]/[HCO 3 - ] = [H 2 CO 3 ][OH - ][H + ] /[HCO 3 - ][H + ] K = K w /Ka1 = 1x /4.5x10 -7 = 2.2x10 -8