1 In Wee Mac’s Sandwich shop, the basic unit is a Wee Mac Dozen (WMD). Slices of bread
(B) weigh 430 g per WMD. Slices of cheese (C) weigh 210 g per WMD. Slices of turkey (T)
weigh 95 g per WMD. Today they are making B2C4T5. At the end of the shift, the total weight
of sandwiches is 65.25 kg. How many sandwiches were made?
a. 30 WMD
b. 40 WMD
c. 50 WMD
d. 60 WMD
e. 142 WMD
—————————
2 In Wee Mac’s Sandwich shop, the basic unit is a Wee Mac Dozen (WMD). Slices of bread
(B) weigh 430 g per WMD. Slices of cheese (C) weigh 210 g per WMD. Slices of turkey (T)
weigh 95 g per WMD.
The sandwich wrapping machine malfunctions one day and all the ingedients end up mixed
together. By weighing a lot of slices of bread, cheese and turkey, it is found that the product
consists of 46.0% bread, and 33.7% cheese. What was the formula of the sandwiches?
a. B2C2T2
b. B2C3T3
c. B2C4T2
d. B2C3T4
e. B2C2T4
—————————
3 In IMEP-107, what percentage of labs returned results for the determination of total arsenic
in rice that were satisfactory, and what percentage returned values for the inorganic arsenic
concentration that were satisfactory (based on the z-scores) ?
a. 100, and 100
b. 33, and 25
c. 77, and 75
d. 75, and 67
e. 75, and 33
—————————
4 In IMEP-107, how many of the expert labs returned results for the determination of total
arsenic in rice and how many returned values for the inorganic arsenic concentration?
a. 7, and 7
b. 6, and 6
c. 8, and 7
d. 7, and 6
e. 100, and 30.
——————————
5 In one molecule of monomethylarsonic acid how many valence electrons are there?
a) 18 b) 24 c) 28 d) 32 e) none of these
——————
6. In the Lewis structure of trimethylarsine As(CH_3)_3 how many lone pairs are on the central
arsenic atom?
a) 0 b) 1 c) 2 d) 3 e) 4
——————————
7 What is the hybridization scheme on the carbon atoms in dichloroethylene?
a) not hybridized b) sp c) sp2 d) sp3 e) sp3d
—————————
8. What is the bond order in the arsenite anion (AsO3^3-)?
a) 1 b) 1.25 c) 1.33 d) 1.5 e) 2al
————————-
9. What is the formal charge on bismuth in bismuthine (bismuth trihydride, BiH_3)
a) 0 b) 1 c) 2 d) -2 e) -1
—————————-
10. In the procedure described by Raber et al. for the determination of arsenic species in rice
a) To oxidize arsenite to arsenate
b) To oxidize arsenate to arsenite
c) To convert all the methylated forms of arsenic to arsenate
d) To extract the arsenic species from the ground rice grain material
e) To convert arsenobetaine to inorganic arsenic.
—————————
11. Which of the following statements about the procedure developed by Raber et al. for the
determination of arsenic species in rice is/are true?
1) The HPLC separation took less than 8 minutes.
2) The detection limit for the inorganic arsenic compounds was 1 µg kg-1.
3) Ion-exchange chromatography was chosen rather than ion-pairing for the HPLC
separation.
4) The extraction involved a 20-times dilution.
5) They obtained inconsistent results for the analysis of NIST SRM 1568a.
a) all b) none c) 3, 4 and 5 d) 1, 2, 3 and 4 e) 1, 2, and 5
———————————-
12. Which of the following statements about the results obtained by Raber et al. for the
determination of arsenic species and total arsenic is/are true?
1. The sum of the concentrations of the species was always greater than the total
concentration.
2. For all of the rice samples, the DMA content was less than the inorganic content.
3. For the rice reference material, the DMA content was higher than the inorganic arsenic
content.
4. Many of the tuna fish samples had DMA concentrations higher than the highest DMA
concentration found in a rice sample.
5. The arsenic concentration in the wheat sample was higher than expected.
6. Low extraction efficiencies were obtained for one or two tuna samples.
a) all b) none c) 1, 2, 3, 4 and 6 d) 1, 2, 5 and 4 e) 2, 3, 4, 5 and 6
———————————-
13. In the Lewis structure of DMA, how many electrons are represented by the line (bonds)
and by the dots (lone pairs).
a) 18 and 8 b) 24 and 8 c) 18 and 6 d) 20 and 12 e) 22 and 10
————————-
14. If a central atom that has one lone pair in a molecule is bound to each of three terminal
atoms by single bonds, the electron pair geometry is
a) tetrahedral b) linear c) trigonal planar d) octahedral e) trigonal bipyramidal
————————————-
15. The best Lewis structure for the sulfate anion (SO42-) is one in which there are two S-toO
single bonds and two S-to-O double bonds. What is the bond order?
a) 1 b) 1.25 c) 1.33 d) 1.5 e) 2
——————————
16.
For which of the following compounds could the molecules be flat molecules?
1) arsenocholine
2) carbon dioxide
3) arsine
4) octane (C8H18)
5) formic acid [HC(O)OH)]
a) all of them b) none of them c) 3, 4 and 5 d) 2 and 5 e) 3
———————————
17. Which of the following compounds has polar molecules?
1) MMA 2) bismuthine 3) water 4) arsenobetaine 5) carbon dioxide
a) all of them b) none of them c) 1, 3, and 4 d) 1, 2, 3, and 4 e) 1, 2,
3, and 5
————————————-
18. Match the shapes with a type of orbital.
———————————————
19. How many sigma (s) bonds and pi (p) bonds are in one molecule of arsenic acid, H3AsO4
?
a) six s, three p b) seven s, one p c) thirteen s, one p d) thirteen s, two p
e) four s, twelve p
——————————-
20. Match the following statements with the research article in which they appear.
A. An improved HPLC-ICP-MS method for determining inorganic arsenic in food: application
to rice, wheat, and tuna fish.
B. Does the determination of inorganic arsenic in rice depend on the method?
1. In the past decade numerous studies on inorganic arsenic contents in rice and rice
products have shown high contents in comparison with those of other food products. Inorganic
arsenic represents very variable percentages of total arsenic (10 – 90%). Because rice is a
staple food and the only source of carbohydrate for many populations throughout the world, a
reliable exhaustive analysis of the inorganic arsenic contents of rice and rice-based food
products is needed.
2. In all cases, the rice samples contained the majority of their arsenic as iAs (25 – 170 µg As
kg-1 representing 57 – 85% of total As).
3. The NIST 1568a Rice Flour is not certified for As species but our results are in good
4. The results show that purely from the analytical point of view, there is no reason not to
consider the option of introducing possible maximum levels for inorganic arsenic in rice.
5. In many cases, however limitations have been imposed by low extraction efficiencies,
digests that are incompatible with HPLC or long HPLC retention times.
———————————
21.
In the De la Calle et al. article, a sentence starts: “In terrestrial organisms, arsenic is mainly
found in the form of dimethylarsinic acid.” What does “terrestrial” mean?
A Causing disease conditions in defined populations.
B Having a backbone.
C Domesticated, as in animals farmed for food.
D Pertaining to the study of the effects of chemicals on living organisms.
E Living on land as opposed to a fresh or seawater environment.
—————————————
22.
Which of the following statements about NIST SRM 1568a are true?
1) It is a standard reference wheat sample from the Instituto Superiore di Sanita in Rome.
2) It is certified reference material supplied by the National Institute of Standards and
Technology in the USA.
3) It is certified for both the inorganic species and total arsenic contents.
4) It is only certified for the total arsenic content of 290 ± 30 µg kg-1.
5) Apart from the results reported by Raber et al., there are only two other reports of the
speciation analysis of this material in the relevant research literature.
a) 1, 3, 4 and 5 b) 1, 3 and 5 c) 4 and 5 d) 2 and 4 e) 2, 3
and 4
————————————-
23. Match the following compounds with the corresponding molecular formula
1) arsenic acid 2) methane 3) trifluoroacetic acid 4) dimethylarsinic acid 5) arsine
A) CH4 B) H3AsO4 C) (CH3)2AsO2H D) CF3CO2H E) AsH3
———————————-
24. For each statement, choose the letter that produces the most accurate statement
concerning the contents the Consumer Reports (Arsenic in your Food) article.
1. The article was published in A) 2008, B) 2009, C) 2012, D) 2011, E) 2010.
2. The food of most concern was A) fish, B) vegetables, C) fruit juice, D) rice, E) bread
3. The number of samples tested was about A) 2000, B) 1000, C) 500, D) 200, E) 20.
5. The main conclusion was A) we should only eat rice grown in the USA, B) there is no need
for concern, C) arsenic concentrations are high enough to be of concern, D) children should not
eat rice products, E) everyone should stop eating rice
———————————-
25. The total arsenic concentration in rice rarely exceeds
a) 10 µg kg-1 b) 1100 µg kg-1 c) 200 µg kg-1 d) 100 µg kg-1 e) 150 µg kg-1
——————
26.
Which of the following statements about the contents of the article by Kevin Francesoni (Analyst
2007, 132, 17-20) are true?
1) The title of the article is “Toxic metal species and food regulations—making a healthy choice”
2) The situations just for arsenic and mercury, two potentially harmful elements, are considered.
3) A detailed comparison is made of the situation for mercury and arsenic in terms of the relative
toxicities of the methylated compounds.
4) The writer concludes that speciation information is necessary to establish the risk of exposure
from the arsenic content of food.
5) The writer points out the key role for the arsenic speciation analyst.
a) all of them b) 1, 2, 3, and 4 c) 2, 3, and 5 d) 1, 3, 4, and 5 e) 2, 3, 4,
and 5
————————————
27. Choose the most appropriate finish to each of the statements about the material in the
article by Andrew Meharg and Andrea Rabb (Env. Sci. Technol. 201, 44, 4395-4399) about the
exposure of consumers to arsenic in drinking water and food.
1) In assessing the potential risks from exposure the writers A) do not think assessing risks
based on extrapolating finds from high dose scenarios is valid, B) consider that there is a
threshold below which there is no risk, C) assume the linear dose-response model.
2) In describing the risks of exposure from drinking water, the writers A) only consider the
current WHO regulation, B) do not mention the current situation in the US, C) describe in detail
why the current US EPA value was chosen, D) focus only on the European standard
3) In discussing the ability of laboratories to make measurements at low concentrations, the
writers point out that A) there are numerous instrumental techniques capable of making relevant
measurements, B) the current methods are unreliable, C) the detection capability of ICP-MS
instruments is such that drinking water standards could by lowered to 0.001 mg L-1 D) not
4) In reviewing the situation with regards to arsenic in food, the writers consider A) that a
measurement of total arsenic in rice could be used as a surrogate for inorganic arsenic, B) the
arsenic concentrations to be too low to be of concern, C) the numerous reference materials
certified for the arsenic species content make speciation analysis the most useful source of
data, D) that the arsenic in seafood is the greatest risk.
5) In discussing ways to decrease exposure to arsenic in the diet the writers A) advocate for
the widespread introduction of genetically modified rice that does not take up arsenic, B) call on
food companies to implement arsenic removal procedures in processing the rice after
harvesting, C) suggest that all food should be cooked in excess water that is discarded, D) point
out that there are detailed studies of agronomic practices to decrease the arsenic content of
rice, E) argue for the elimination of rice from the diet.
———————————-
28. Which of the following statements appear in the article by Zavala et al. (Arsenic in Rice II.
Arsenic speciation in USA grain and implications for human health, Env. Sci. Technol. 2008, 42,
3861-3866)?
1) Although inorganic arsenic is thought to be more harmful than DMA, further
epidemiological studies are needed to better understand the health risks of DMA.
2) Plant breeding to convert currently popular inorganic arsenic rice type varieties around the
world to the DMA type would be an important risk reduction strategy.
3) Twenty-four sample of US rice at the higher end of the range of observed total arsenic
concentration and representing rice grown in Texas (n = 16), Arkansas (n = 3) and California (n
= 5) were selected from the market basket study of Zavala and Duxbury.
4) A striking pattern for arsenic speciation emerged when individual species data were plotted
against the sum of species measure of total arsenic.
5) The increasing concern about dietary intake of inorganic arsenic, combined with possible
future legislative regulations, highlights the need for a selective, sensitive and robust method for
determining the inorganic arsenic content of food covering a range of matrices.
a) all of them b) 2, 3, and 4 c) 1, 2, 3, and 5 d) 2, 3, 4, and 5 e) 1, 2, 3,
and 4
——————————————
29. Which of the following statements about the contents of the article by Gilbert Diamond et
al. (PNAS, 2011, 108 20656-20660) is/are true?
1) The article describes work that was done at both Dartmouth College and the University of
Arizona, Tuscon.
2) The speciation measurements were made by Applied Speciation and Consulting LLC at
the laboratory facility in Tukwila WA.
3) The researchers conclude that rice consumption should be considered when designing
arsenic reduction strategies in the United States.
4) The researchers consider that fetal development represents a particularly vulnerable
window of arsenic exposure, with both immediate and long-term health risks.
5) The researchers argue that the large and statistically significant association they found
observed between rice consumption and urinary arsenic underscores the need to regulate
arsenic in food.
a) all of them b) 1, 2, 4 and 5 c) 1, 3, 4, and 5 d) 2 e) 1, 4 and
5.
—————————————
30. Match the following statements with the article from which they were taken
1) Thus a major difference in seafood mercury and seafood arsenic is apparent—although the
inorganic forms of both mercury and arsenic are toxic, methylation of mercury produces the
more toxic MeHg+ species whereas methylation of arsenic produces, as an end product, the
innocuous arsenobetaine and both species occur at elevated concentrations in seafoods.
2) In the past decade, numerous studies on inorganic arsenic contents in rice and rice
products have shown high contents in comparison with those of other food products. Inorganic
arsenic represents very variable percentages of total arsenic (10 – 90%). Because rice is a
staple food and the only source of carbohydrate for many populations throughout the world, a
reliable exhaustive analysis of the inorganic arsenic contents of rice and rice-based food
products is needed.
3) While there is considerable debate as to whether epidemiological studies conducted on
highly exposed populations used to derive dose-response relationships can be extrapolated to
low-dose scenarios, we have to assume the linear dose-response model until proven otherwise.
4) We also discovered that some infant rice cereals, which are often a baby’s first solid food,
had levels of inorganic arsenic at least five times more than has been found in alternatives such
as oatmeal. Given our findings, we suggest limiting the consumption of rice products.
5) In many cases, however, limitations have been imposed by low extraction efficiencies,
digests that are incompatible with HPLC, or long HPLC retention times.
B. Toxic metal species and food regulations—making a healthy choice
C. Getting to the bottom of arsenic standards and guidelines.
D. Arsenic in Rice: II. Arsenic speciation in USA grain and implications for human health
E. Rice consumption contributes to arsenic exposure in women
F. An improved HPLC-ICPMS method for determining inorganic arsenic in food: application to
rice, wheat and tuna fish.
G. Does the determination of inorganic arsenic depend on the method?
——————————————
31. A rice sample was analyzed as received for the total arsenic content by the method of
Raber et al., in which a 250 mg sample was dissolved in 10 mL of solution, which was then
analyzed by ICP-MS. The solution contained 6.4 µg L-1 of arsenic. In a separate experiment,
the moisture content of the rice was determined to be 10%. What was the concentration of
arsenic on a dry weight basis in µg kg-1?
a) 256 b) 255 c) 224 d) 284 e) 251
———————————
32. What is the molecular weight of MMA in g mol-1?
a) 138.10 b) 139.98 c) 138.01 d) 193.98 e) 138.89
————————————
33. Chemical analysis of a pure arsenic compound containing only C, H, O, and As found that
the percentage composition by weight was C 17.4%, H 5.12%, and As 54.29%. What is the
identity of the compound?
a) arsenic acid b) arsenobetaine c) lead arsenate d) trimethylarsine oxide e) DMA
—————————————
34. When the expression for the reaction between arsenite and permanganate (MnO4-) in
acid solution to give arsenate, the manganous ion (Mn2+) and water is balanced, the values of
the letters A, B, C, E, and F are
A H3AsO3 + B MnO4- + C H+ ? D H3AsO4 + E Mn2+ + F H2O
———————————————
35. A sample of pressure-treated wood weighing 0.3245 g was dissolved in concentrated nitric
acid to convert all of the arsenic to arsenate. The solution was diluted 10 times and excess
silver added to precipitate silver arsenate (Ag3AsO4), which was collected dried and weighed.
If the mass of the precipitate was 0.0453 g what is the percentage of arsenic in the wood?
a) 2.26 b) 9.03 c) 22.5 d) 2.24 ) 3.01
———————————————-
36. A sample of an arsenic compound weighing 0.1023 g was dissolved and all the arsenic
converted to arsenic in the +3 oxidation state. A 0.0250 M solution of an acidified
permanganate (MnO4-), was added, which oxidized the arsenic to the +5 oxidation state. The
manganese was reduced to the +2 state. If it took 10.64 mL of the permanganate solution to
exactly react with the arsenic, what is the percentage of arsenic in the sample?
a) 42.5 b) 47.8 c) 7.79 d) 19.5 e) 48.7
——————————————-
37. At the food processing plant, rice from three storage bins, A, B and C is mixed in unequal
quantities before the bags are filled. The ratio of the weight of rice mixed is 1:2:3 (A:B:C) and
the concentrations of total arsenic of the rice in each bin are 100, 160 and 240 µg kg-1,
respectively. What is the concentration of arsenic in the bags in µg kg-1?
a) 190 b) 168 c) 83.3 d) 100 e) none of these
———————————-
38. If you eat a 48 g serving rice every fourth day and you weigh 75 kg, what is your dose of
inorganic arsenic (in µg per kg body weight per day) if the rice contains 386 µg kg-1 of total
arsenic, 45% of which is inorganic arsenic.
a) 0.28 b) 278 c) 0.11 d) 0.028 e) 0.030
————————————
39. Which of the following statements is/are false?
1) To convert mL to L, multiply by 1000.
2) To convert µg to mg, divide by 1000.
3) To convert mass to amount in mol, divide by the molecular/atomic weight.
4) To convert concentration in percent to concentration in parts per million, multiply by 106.
5) One ppb is equivalent to 1 ng per g.
6) One ppb is equivalent to 1 µg kg-1.
7) To convert kg to g, multiply by 1000.
8) Concentration in a solid material is the mass fraction multiplied by an appropriate scaling
factor.
9) Parts per million is the same as percent.
10) In solution, 1 ppb is equivalent to 1 ng mL-1.
a) 1, 2, 4, and 7 b) 1, 4, and 10 c) 1, 4, and 9 d) 4 and 9 e) 2 and 7
—————————-
40. Many scientists are using 3.7 (mg per kg bw per d)-1 as the current value for the slope of
the dose-response curve for inorganic arsenic and excess lifetime risk of lung cancer. What
dose in (µg per kg bw per d) corresponds to an excess lifetime risk of 1 in 2500?
a) 0.11 b) 0.15 c) 1.8 d) 0.81 e) 0.18
——————————————

## "Are you looking for this answer? We can Help click Order Now"

1 In Wee Mac’s Sandwich shop, the basic unit is a Wee Mac Dozen (WMD). Slices of bread
(B) weigh 430 g per WMD. Slices of cheese (C) weigh 210 g per WMD. Slices of turkey (T)
weigh 95 g per WMD. Today they are making B2C4T5. At the end of the shift, the total weight
of sandwiches is 65.25 kg. How many sandwiches were made?
a. 30 WMD
b. 40 WMD
c. 50 WMD
d. 60 WMD
e. 142 WMD
—————————
2 In Wee Mac’s Sandwich shop, the basic unit is a Wee Mac Dozen (WMD). Slices of bread
(B) weigh 430 g per WMD. Slices of cheese (C) weigh 210 g per WMD. Slices of turkey (T)
weigh 95 g per WMD.
The sandwich wrapping machine malfunctions one day and all the ingedients end up mixed
together. By weighing a lot of slices of bread, cheese and turkey, it is found that the product
consists of 46.0% bread, and 33.7% cheese. What was the formula of the sandwiches?
a. B2C2T2
b. B2C3T3
c. B2C4T2
d. B2C3T4
e. B2C2T4
—————————
3 In IMEP-107, what percentage of labs returned results for the determination of total arsenic
in rice that were satisfactory, and what percentage returned values for the inorganic arsenic
concentration that were satisfactory (based on the z-scores) ?
a. 100, and 100
b. 33, and 25
c. 77, and 75
d. 75, and 67
e. 75, and 33
—————————
4 In IMEP-107, how many of the expert labs returned results for the determination of total
arsenic in rice and how many returned values for the inorganic arsenic concentration?
a. 7, and 7
b. 6, and 6
c. 8, and 7
d. 7, and 6
e. 100, and 30.
——————————
5 In one molecule of monomethylarsonic acid how many valence electrons are there?
a) 18 b) 24 c) 28 d) 32 e) none of these
——————
6. In the Lewis structure of trimethylarsine As(CH_3)_3 how many lone pairs are on the central
arsenic atom?
a) 0 b) 1 c) 2 d) 3 e) 4
——————————
7 What is the hybridization scheme on the carbon atoms in dichloroethylene?
a) not hybridized b) sp c) sp2 d) sp3 e) sp3d
—————————
8. What is the bond order in the arsenite anion (AsO3^3-)?
a) 1 b) 1.25 c) 1.33 d) 1.5 e) 2al
————————-
9. What is the formal charge on bismuth in bismuthine (bismuth trihydride, BiH_3)
a) 0 b) 1 c) 2 d) -2 e) -1
—————————-
10. In the procedure described by Raber et al. for the determination of arsenic species in rice
a) To oxidize arsenite to arsenate
b) To oxidize arsenate to arsenite
c) To convert all the methylated forms of arsenic to arsenate
d) To extract the arsenic species from the ground rice grain material
e) To convert arsenobetaine to inorganic arsenic.
—————————
11. Which of the following statements about the procedure developed by Raber et al. for the
determination of arsenic species in rice is/are true?
1) The HPLC separation took less than 8 minutes.
2) The detection limit for the inorganic arsenic compounds was 1 µg kg-1.
3) Ion-exchange chromatography was chosen rather than ion-pairing for the HPLC
separation.
4) The extraction involved a 20-times dilution.
5) They obtained inconsistent results for the analysis of NIST SRM 1568a.
a) all b) none c) 3, 4 and 5 d) 1, 2, 3 and 4 e) 1, 2, and 5
———————————-
12. Which of the following statements about the results obtained by Raber et al. for the
determination of arsenic species and total arsenic is/are true?
1. The sum of the concentrations of the species was always greater than the total
concentration.
2. For all of the rice samples, the DMA content was less than the inorganic content.
3. For the rice reference material, the DMA content was higher than the inorganic arsenic
content.
4. Many of the tuna fish samples had DMA concentrations higher than the highest DMA
concentration found in a rice sample.
5. The arsenic concentration in the wheat sample was higher than expected.
6. Low extraction efficiencies were obtained for one or two tuna samples.
a) all b) none c) 1, 2, 3, 4 and 6 d) 1, 2, 5 and 4 e) 2, 3, 4, 5 and 6
———————————-
13. In the Lewis structure of DMA, how many electrons are represented by the line (bonds)
and by the dots (lone pairs).
a) 18 and 8 b) 24 and 8 c) 18 and 6 d) 20 and 12 e) 22 and 10
————————-
14. If a central atom that has one lone pair in a molecule is bound to each of three terminal
atoms by single bonds, the electron pair geometry is
a) tetrahedral b) linear c) trigonal planar d) octahedral e) trigonal bipyramidal
————————————-
15. The best Lewis structure for the sulfate anion (SO42-) is one in which there are two S-toO
single bonds and two S-to-O double bonds. What is the bond order?
a) 1 b) 1.25 c) 1.33 d) 1.5 e) 2
——————————
16.
For which of the following compounds could the molecules be flat molecules?
1) arsenocholine
2) carbon dioxide
3) arsine
4) octane (C8H18)
5) formic acid [HC(O)OH)]
a) all of them b) none of them c) 3, 4 and 5 d) 2 and 5 e) 3
———————————
17. Which of the following compounds has polar molecules?
1) MMA 2) bismuthine 3) water 4) arsenobetaine 5) carbon dioxide
a) all of them b) none of them c) 1, 3, and 4 d) 1, 2, 3, and 4 e) 1, 2,
3, and 5
————————————-
18. Match the shapes with a type of orbital.
———————————————
19. How many sigma (s) bonds and pi (p) bonds are in one molecule of arsenic acid, H3AsO4
?
a) six s, three p b) seven s, one p c) thirteen s, one p d) thirteen s, two p
e) four s, twelve p
——————————-
20. Match the following statements with the research article in which they appear.
A. An improved HPLC-ICP-MS method for determining inorganic arsenic in food: application
to rice, wheat, and tuna fish.
B. Does the determination of inorganic arsenic in rice depend on the method?
1. In the past decade numerous studies on inorganic arsenic contents in rice and rice
products have shown high contents in comparison with those of other food products. Inorganic
arsenic represents very variable percentages of total arsenic (10 – 90%). Because rice is a
staple food and the only source of carbohydrate for many populations throughout the world, a
reliable exhaustive analysis of the inorganic arsenic contents of rice and rice-based food
products is needed.
2. In all cases, the rice samples contained the majority of their arsenic as iAs (25 – 170 µg As
kg-1 representing 57 – 85% of total As).
3. The NIST 1568a Rice Flour is not certified for As species but our results are in good
4. The results show that purely from the analytical point of view, there is no reason not to
consider the option of introducing possible maximum levels for inorganic arsenic in rice.
5. In many cases, however limitations have been imposed by low extraction efficiencies,
digests that are incompatible with HPLC or long HPLC retention times.
———————————
21.
In the De la Calle et al. article, a sentence starts: “In terrestrial organisms, arsenic is mainly
found in the form of dimethylarsinic acid.” What does “terrestrial” mean?
A Causing disease conditions in defined populations.
B Having a backbone.
C Domesticated, as in animals farmed for food.
D Pertaining to the study of the effects of chemicals on living organisms.
E Living on land as opposed to a fresh or seawater environment.
—————————————
22.
Which of the following statements about NIST SRM 1568a are true?
1) It is a standard reference wheat sample from the Instituto Superiore di Sanita in Rome.
2) It is certified reference material supplied by the National Institute of Standards and
Technology in the USA.
3) It is certified for both the inorganic species and total arsenic contents.
4) It is only certified for the total arsenic content of 290 ± 30 µg kg-1.
5) Apart from the results reported by Raber et al., there are only two other reports of the
speciation analysis of this material in the relevant research literature.
a) 1, 3, 4 and 5 b) 1, 3 and 5 c) 4 and 5 d) 2 and 4 e) 2, 3
and 4
————————————-
23. Match the following compounds with the corresponding molecular formula
1) arsenic acid 2) methane 3) trifluoroacetic acid 4) dimethylarsinic acid 5) arsine
A) CH4 B) H3AsO4 C) (CH3)2AsO2H D) CF3CO2H E) AsH3
———————————-
24. For each statement, choose the letter that produces the most accurate statement
concerning the contents the Consumer Reports (Arsenic in your Food) article.
1. The article was published in A) 2008, B) 2009, C) 2012, D) 2011, E) 2010.
2. The food of most concern was A) fish, B) vegetables, C) fruit juice, D) rice, E) bread
3. The number of samples tested was about A) 2000, B) 1000, C) 500, D) 200, E) 20.
5. The main conclusion was A) we should only eat rice grown in the USA, B) there is no need
for concern, C) arsenic concentrations are high enough to be of concern, D) children should not
eat rice products, E) everyone should stop eating rice
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25. The total arsenic concentration in rice rarely exceeds
a) 10 µg kg-1 b) 1100 µg kg-1 c) 200 µg kg-1 d) 100 µg kg-1 e) 150 µg kg-1
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26.
Which of the following statements about the contents of the article by Kevin Francesoni (Analyst
2007, 132, 17-20) are true?
1) The title of the article is “Toxic metal species and food regulations—making a healthy choice”
2) The situations just for arsenic and mercury, two potentially harmful elements, are considered.
3) A detailed comparison is made of the situation for mercury and arsenic in terms of the relative
toxicities of the methylated compounds.
4) The writer concludes that speciation information is necessary to establish the risk of exposure
from the arsenic content of food.
5) The writer points out the key role for the arsenic speciation analyst.
a) all of them b) 1, 2, 3, and 4 c) 2, 3, and 5 d) 1, 3, 4, and 5 e) 2, 3, 4,
and 5
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27. Choose the most appropriate finish to each of the statements about the material in the
article by Andrew Meharg and Andrea Rabb (Env. Sci. Technol. 201, 44, 4395-4399) about the
exposure of consumers to arsenic in drinking water and food.
1) In assessing the potential risks from exposure the writers A) do not think assessing risks
based on extrapolating finds from high dose scenarios is valid, B) consider that there is a
threshold below which there is no risk, C) assume the linear dose-response model.
2) In describing the risks of exposure from drinking water, the writers A) only consider the
current WHO regulation, B) do not mention the current situation in the US, C) describe in detail
why the current US EPA value was chosen, D) focus only on the European standard
3) In discussing the ability of laboratories to make measurements at low concentrations, the
writers point out that A) there are numerous instrumental techniques capable of making relevant
measurements, B) the current methods are unreliable, C) the detection capability of ICP-MS
instruments is such that drinking water standards could by lowered to 0.001 mg L-1 D) not
4) In reviewing the situation with regards to arsenic in food, the writers consider A) that a
measurement of total arsenic in rice could be used as a surrogate for inorganic arsenic, B) the
arsenic concentrations to be too low to be of concern, C) the numerous reference materials
certified for the arsenic species content make speciation analysis the most useful source of
data, D) that the arsenic in seafood is the greatest risk.
5) In discussing ways to decrease exposure to arsenic in the diet the writers A) advocate for
the widespread introduction of genetically modified rice that does not take up arsenic, B) call on
food companies to implement arsenic removal procedures in processing the rice after
harvesting, C) suggest that all food should be cooked in excess water that is discarded, D) point
out that there are detailed studies of agronomic practices to decrease the arsenic content of
rice, E) argue for the elimination of rice from the diet.
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28. Which of the following statements appear in the article by Zavala et al. (Arsenic in Rice II.
Arsenic speciation in USA grain and implications for human health, Env. Sci. Technol. 2008, 42,
3861-3866)?
1) Although inorganic arsenic is thought to be more harmful than DMA, further
epidemiological studies are needed to better understand the health risks of DMA.
2) Plant breeding to convert currently popular inorganic arsenic rice type varieties around the
world to the DMA type would be an important risk reduction strategy.
3) Twenty-four sample of US rice at the higher end of the range of observed total arsenic
concentration and representing rice grown in Texas (n = 16), Arkansas (n = 3) and California (n
= 5) were selected from the market basket study of Zavala and Duxbury.
4) A striking pattern for arsenic speciation emerged when individual species data were plotted
against the sum of species measure of total arsenic.
5) The increasing concern about dietary intake of inorganic arsenic, combined with possible
future legislative regulations, highlights the need for a selective, sensitive and robust method for
determining the inorganic arsenic content of food covering a range of matrices.
a) all of them b) 2, 3, and 4 c) 1, 2, 3, and 5 d) 2, 3, 4, and 5 e) 1, 2, 3,
and 4
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29. Which of the following statements about the contents of the article by Gilbert Diamond et
al. (PNAS, 2011, 108 20656-20660) is/are true?
1) The article describes work that was done at both Dartmouth College and the University of
Arizona, Tuscon.
2) The speciation measurements were made by Applied Speciation and Consulting LLC at
the laboratory facility in Tukwila WA.
3) The researchers conclude that rice consumption should be considered when designing
arsenic reduction strategies in the United States.
4) The researchers consider that fetal development represents a particularly vulnerable
window of arsenic exposure, with both immediate and long-term health risks.
5) The researchers argue that the large and statistically significant association they found
observed between rice consumption and urinary arsenic underscores the need to regulate
arsenic in food.
a) all of them b) 1, 2, 4 and 5 c) 1, 3, 4, and 5 d) 2 e) 1, 4 and
5.
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30. Match the following statements with the article from which they were taken
1) Thus a major difference in seafood mercury and seafood arsenic is apparent—although the
inorganic forms of both mercury and arsenic are toxic, methylation of mercury produces the
more toxic MeHg+ species whereas methylation of arsenic produces, as an end product, the
innocuous arsenobetaine and both species occur at elevated concentrations in seafoods.
2) In the past decade, numerous studies on inorganic arsenic contents in rice and rice
products have shown high contents in comparison with those of other food products. Inorganic
arsenic represents very variable percentages of total arsenic (10 – 90%). Because rice is a
staple food and the only source of carbohydrate for many populations throughout the world, a
reliable exhaustive analysis of the inorganic arsenic contents of rice and rice-based food
products is needed.
3) While there is considerable debate as to whether epidemiological studies conducted on
highly exposed populations used to derive dose-response relationships can be extrapolated to
low-dose scenarios, we have to assume the linear dose-response model until proven otherwise.
4) We also discovered that some infant rice cereals, which are often a baby’s first solid food,
had levels of inorganic arsenic at least five times more than has been found in alternatives such
as oatmeal. Given our findings, we suggest limiting the consumption of rice products.
5) In many cases, however, limitations have been imposed by low extraction efficiencies,
digests that are incompatible with HPLC, or long HPLC retention times.
B. Toxic metal species and food regulations—making a healthy choice
C. Getting to the bottom of arsenic standards and guidelines.
D. Arsenic in Rice: II. Arsenic speciation in USA grain and implications for human health
E. Rice consumption contributes to arsenic exposure in women
F. An improved HPLC-ICPMS method for determining inorganic arsenic in food: application to
rice, wheat and tuna fish.
G. Does the determination of inorganic arsenic depend on the method?
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31. A rice sample was analyzed as received for the total arsenic content by the method of
Raber et al., in which a 250 mg sample was dissolved in 10 mL of solution, which was then
analyzed by ICP-MS. The solution contained 6.4 µg L-1 of arsenic. In a separate experiment,
the moisture content of the rice was determined to be 10%. What was the concentration of
arsenic on a dry weight basis in µg kg-1?
a) 256 b) 255 c) 224 d) 284 e) 251
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32. What is the molecular weight of MMA in g mol-1?
a) 138.10 b) 139.98 c) 138.01 d) 193.98 e) 138.89
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33. Chemical analysis of a pure arsenic compound containing only C, H, O, and As found that
the percentage composition by weight was C 17.4%, H 5.12%, and As 54.29%. What is the
identity of the compound?
a) arsenic acid b) arsenobetaine c) lead arsenate d) trimethylarsine oxide e) DMA
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34. When the expression for the reaction between arsenite and permanganate (MnO4-) in
acid solution to give arsenate, the manganous ion (Mn2+) and water is balanced, the values of
the letters A, B, C, E, and F are
A H3AsO3 + B MnO4- + C H+ ? D H3AsO4 + E Mn2+ + F H2O
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35. A sample of pressure-treated wood weighing 0.3245 g was dissolved in concentrated nitric
acid to convert all of the arsenic to arsenate. The solution was diluted 10 times and excess
silver added to precipitate silver arsenate (Ag3AsO4), which was collected dried and weighed.
If the mass of the precipitate was 0.0453 g what is the percentage of arsenic in the wood?
a) 2.26 b) 9.03 c) 22.5 d) 2.24 ) 3.01
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36. A sample of an arsenic compound weighing 0.1023 g was dissolved and all the arsenic
converted to arsenic in the +3 oxidation state. A 0.0250 M solution of an acidified
permanganate (MnO4-), was added, which oxidized the arsenic to the +5 oxidation state. The
manganese was reduced to the +2 state. If it took 10.64 mL of the permanganate solution to
exactly react with the arsenic, what is the percentage of arsenic in the sample?
a) 42.5 b) 47.8 c) 7.79 d) 19.5 e) 48.7
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37. At the food processing plant, rice from three storage bins, A, B and C is mixed in unequal
quantities before the bags are filled. The ratio of the weight of rice mixed is 1:2:3 (A:B:C) and
the concentrations of total arsenic of the rice in each bin are 100, 160 and 240 µg kg-1,
respectively. What is the concentration of arsenic in the bags in µg kg-1?
a) 190 b) 168 c) 83.3 d) 100 e) none of these
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38. If you eat a 48 g serving rice every fourth day and you weigh 75 kg, what is your dose of
inorganic arsenic (in µg per kg body weight per day) if the rice contains 386 µg kg-1 of total
arsenic, 45% of which is inorganic arsenic.
a) 0.28 b) 278 c) 0.11 d) 0.028 e) 0.030
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39. Which of the following statements is/are false?
1) To convert mL to L, multiply by 1000.
2) To convert µg to mg, divide by 1000.
3) To convert mass to amount in mol, divide by the molecular/atomic weight.
4) To convert concentration in percent to concentration in parts per million, multiply by 106.
5) One ppb is equivalent to 1 ng per g.
6) One ppb is equivalent to 1 µg kg-1.
7) To convert kg to g, multiply by 1000.
8) Concentration in a solid material is the mass fraction multiplied by an appropriate scaling
factor.
9) Parts per million is the same as percent.
10) In solution, 1 ppb is equivalent to 1 ng mL-1.
a) 1, 2, 4, and 7 b) 1, 4, and 10 c) 1, 4, and 9 d) 4 and 9 e) 2 and 7
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40. Many scientists are using 3.7 (mg per kg bw per d)-1 as the current value for the slope of
the dose-response curve for inorganic arsenic and excess lifetime risk of lung cancer. What
dose in (µg per kg bw per d) corresponds to an excess lifetime risk of 1 in 2500?
a) 0.11 b) 0.15 c) 1.8 d) 0.81 e) 0.18
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