Practice Final December, 2006

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Practice Final December, 2006
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• 1.      The oxidation state of sulfur (S) in
  SO42- is
• (a) 6 (b) 4
  (c) 2 (d) 0
• (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.

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• 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

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• 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  

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• 7. Most of the mercury present in humans is in
  the form of
• (a) Hgo (b) Hg22 (c) Hg2 (d)
  methylmercury
•   (d) methylmercury
•  
• 8-12. Given the dissociation constant for acetic
  acid 1.8 x10-5. (a) Calculate the pH for a
  0.04 M solution of acetic acid, HOAc.
•    HOAc ? H Oac- Ka
  1.8x10-5
•    0.04 - -
  
•   0.04-x x x
• xx/0.04 1.8x10-5
• x2 7.2 x10-7 x
  8.48x10-4 pH 3.07

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• (b) What would be the pH if 0.01 M NaOAc were
  added to the solution.
• HOAc ? H OAc-
  Ka 1.8x10-5
• 0.04 -
  0.01
• 0.04-x x
  0.01 x
  
• x0.01/0.04 1.8 x
  10-5
•   x 7.2 x 10-5
•   pH 4.14
•  

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•  13.  The two figures show the dose-response
  curves for exposure of two organisms to a
  specific toxicant.
• (a)    both curves have the same EC50 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 EC50 values

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• 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 CaCO3 by
  CaSO4 on historical monuments.
• (c) trees at high altitudes are least affected
  by acid rain due to protection of low-lying
  clouds.  
•  
• 15-17. Given KH(Henry's law constant)
  3.38x10-2 moles L-1 atm-1 and Ka1 4.45x10-7
  for carbonic acid (H2CO3), calculate the pH of
  water in equilibrium with CO2 in the atmosphere
  where the concentration of CO2 316 ppm.
•   H2CO3 3.16x10-4 x 3.38 x10-2
•   H2CO3 1.06
  x 10-5
•    H2CO3 ? H
  HCO3-1
• 1.06x10-5 -x x
  x
• xx 4.7x10-12 x
  2.1x10-6 pH 5.68
•  

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• 18. Which one of the following ions is
  responsible for making water "hard"?
• a. Na b. Mg2 c.
  SO42- d. CO32-
•   b. Mg2
•  

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• 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
•  
• 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  

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• 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 H2CO3,
  HCO3-, CO32- fractions in natural water as
  functions of pH.
•  
• The line B represents
•  
• (a) H2CO3 (b) HCO3-
• (c) CO32- (d) H2O 
• b) HCO3-

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• 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
• 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 

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• 29. CH3Hg and (CH3)2Hg 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.
  

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• Questions 31-33 relate to this figure which shows
  the biological response of organisms to toxicant
  concentrations
•  
• Region C represents
• (a)    no toxic effect (b) irreversible effects
• (b)   death (d) none of these
• (b) irreversible effects
•  
• 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
• Acute toxicity testing occurs in
• (a) Region A (b) Region B (c) Region C
  (d) Region D
•  (d) Region D

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•  34. In the use of hypochlorous acid, HOCl as a
  disinfectant, the pH is maintained around 7.5 to
• (a) increase the solubility of Cl2 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) ClO2 (b) H2O2 (c) UV light (d) O3
•   (b) H2O2
• . 36. Which of the following compounds is a
  xenobiotic substance?
• (a) N2O (b) CO2 (c) CHCl3 (d) O3
• (c) CHCl3

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• 37. The trace greenhouse gases methane, nitrous
  oxide, and CFCs will likely have a combined
  effect comparable to CO2 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. N2 b. O2
  c. CO2 d. Ar
•   c. CO2
•  

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• 40. Which of the following reactions is
  representative of hydroxyl free radical
  chemistry?
• (a) CHCl3 OH --------- CHCl2OH
  Cl
• (b) CHCl3 OH ---------- CHCl2
  HCl
• (c) OH(g) NO2(g)-------M-----
  HNO3(g)
• (d) CHCl3 OH ----------- CH2OCl
  Cl2
•  (c) OH(g) NO2(g)-------M-----
  HNO3(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) NO2 ----hn,l NO O
• (b) O2 NO2 ----------------- NO
  O3
• (c) O3 -------hn,l O2
  O
• (d) O H2O ---------- 2 OH (where O is
  an excited oxygen atom)
• (b) O2 NO2 ----------------- NO
  O3

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•  
• 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) HSO3 NO -------- NO2 HSO2
• (b) H2O2 ----------- H2
  O2
• (c) CH3COO OH ---------- CH3COH
  O2
• (d) HSO2 OH -------- H2SO3
•  (a) HSO3 NO -------- NO2 HSO2
•  
• 43. Which of the following reactions takes place
  in a catalytic converter
• (a) OH SO2 -------- HSO3
• (b) CO2 1/2 N2 ------- CO NO
• (c) H2 NOx --------- N2 H2O
• (d) 1/2 O2 NO ---------- NO2
•  (c) H2 NOx --------- N2 H2O

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•  
• 45-50. Given the following equilibria constants
• H2CO3 ----- H HCO3- Ka1
  4.5 x 10-7
• HCO3- ------ H CO32-
  Ka2 4.7 x 10-11
• CaCO3 ------ Ca2 CO32-
  Ksp 4.6 x 10-9
• calculate the equilibrium constant for the
  reaction
• HCO3- H2O -------- H2CO3 OH-
• K H2CO3OH-/HCO3- H2CO3OH-H
  /HCO3-H
• K Kw/Ka1 1x10-14/4.5x10-7 2.2x10-8