Chem 100- Exam 1
Statistical Summary
Your exam score is the sum of
- a. the total on part 1 (bottom of the page 1)
- b. twice the number of correct responses on computer scan
- 30 questions, points available: 60
- total is out of 100 points
-
(The total was not reported on the exam)
- The answers have been posted on the class Web site
The distribution of scores
- Part I -- Class Average = 26.0 (out of 40)
- Part II -- Class Average = 17.9 correct answers (out of 30)
- 35.8 points out of
- Total-- Class Average = 62.2
- Frequency Chart
- 90-99 (5)
- 80-89 (13)
- 70-79 (35)
- 60-69 (59)
- 50-59 (52)
- 40-49 (16)
- below 40 (9)
- The syllabus listed a grading scale
- A = 93% and higher
B=81-92%
C= 66-80%
D= 60-65%
F < 60%
- That scale is probably a little severe for this exam and will be adjusted slightly
- A passing grade would be around 55%
- Part II (correct answers)
- 6 correct, [2 papers]
- 8 correct, [2 papers]
- 9 correct, [2 papers]
- 10 correct, [2 papers]
- 12 correct, [4 papers]
- 13 correct, [9 papers]
- 14 correct, [9 papers]
- 15 correct, [23 papers]
- 16 correct, [13 papers]
- 17 correct, [20 papers]
- 18 correct, [21 papers]
- 19 correct, [26 papers]
- 20 correct, [18 papers]
- 21 correct, [5 papers]
- 22 correct, [7 papers]
- 23 correct, [7 papers]
- 24 correct, [4 papers]
- 25 correct, [4 papers]
- 26 correct, [7 papers]
- 27 correct, [3 papers]
- 28 correct, [1 papers]
- 30 correct, [1 papers]
Part II -- selected Multiple Choice Questions
These were questions with a class response of 50% or less. The sequence is that of form A-- your exam may have had the questions in a different order
- [38%] is the percentage of correct responses-- that is 38% of the papers had this correct
- [25] at end of a response means 25 such responses out of 65 papers studied
2. [38%] The
nitrogen you breathe as you inhale air
-
a. plays no significant chemical role in your body [25]
b. is converted by your body to ammonia (NH3) [2]
- c. is used by your body to create proteins [8]
- d. is converted in your body to Nitrogen Oxide [17]
- e. is toxic at concentrations in excess of 300 parts per million [12]
12. [26%]At a temperature of 32
o Celsius (Centigrade)
- a. liquid nitrogen would remain a liquid [16]
- b. water would begin to freeze [22]
-
c. coffee would be hot, yet drinkable (assuming you like coffee) [17]
d. water would begin to boil [8]
- e. metals like Tin would begin to melt [2]
16. [29%] The element
S (atomic number 16-- see periodic table on page 1)
- a. is likely to form a +2 Ion [16]
- b. is likely to form a -1 Ion [22]
- c. is likely to be very inert [17]
-
d. probably forms a compound H2S with Hydrogen [8]
- e. probably has chemical properties most similar to those of neighboring elements
P (atomic number 15) and
Cl (atomic number 17) [2]
17. [26%] The molecular weight of carbon dioxide is
44.0 One mole of CO2
-
a. has a mass of (1 / 44.0) grams [22]
b. has a mass of 44 grams [8]
- c. has a mass of 44 kilograms [6]
- d. has a mass of 6.023 x 10-23 grams [19]
- e. has the same mass as one mole of any other chemical compound [10]
19. [23%] Element of the day-- Which statement below is
NOT true
- a. The sodium ion is very unreactive (boring) [39]
- b. Gold metal is useful because it is chemically u]nreactive (boring) [3
- c. Iodine (I2) is useful as a disinfectant because it is reactive [5]
-
d. Bronze is an ancient term for what we now call copper [15]
e. Gold and Copper were used long before the Iron Age. [3]
20. [43%] One atom of the isotope
2311Na
- a. contains 11 neutrons [12]
- b. contains 23 electrons [15]
- c. contains 11 electrons [28]
- d. contains 12 protons [9]
- e. contains 11 sodium nuclei [1]
21.[34%] In a chemical reaction
- a.
The mass of reactants = the mass of products [22]
b. The number of reactant molecules = number of product molecules [17]
- c. Volume of reactant = volume of products [1]
- d. The reactants are chemical elements and the products are chemical compounds [ 23]
- e. Atoms may change into atoms of lower atomic mass but not higher atomic mass [2]
23. [31%] Which type of radiation possesses the most energy (per photon)
- a. red light [4]
- b. blue light [1]
-
c. ultraviolet light [31]
d. infrared light [11]
- e. microwaves [18]
24. [43%] The burning of fossil fuels is considered a key component in global warming. This is because
burning these fuels produces CO2 and
- a. Burning the fuels produces heat[ 9]
-
b. CO2 is a species that can prevent the escape of infrared radiation [28]
c. CO2 is very efficient at absorbing sunlight [15]
- d. CO2 from fossil fuels contains little or no 14C due to their age [1]
- e. The earth lacks a mechanism for the removal of CO2 [12]
27. [45%] The Periodic Table contains about 110 Chemical elements. Which statement best describes
these elements
- a. over half of the elements are gases or liquids at room temperature [3]
-
b. over half of the elements are classified as metals [29]
- c. the elements in the center block of the table are called Halogens [0]
- d. the first column (I-A) contains the Inert Gases (also called the Noble Gases) [5]
- e. all the elements occur naturally in the earth or atmosphere, although some are present at very low concentrations. [28]
30. [29%] Which of the statements about ionic species is
NOT true
- a. Ionic compounds always include both positive and negative ions[ 12]
- b. Ions can contain several atoms within a single ion. [16]
- c. An Na+ ion contains fewer electrons than a sodium atom[ 15]
-
d. Calcium Chloride, CaCl2, is an ionic compound with one calcium ion and two chloride ions in each calcium chloride molecule [19]
e. Water (H2O) is not an ionic compound [3]
Selected Questions in Part I (written responses)
- There were three versions of the exam and the questions differed somewhat. They did have the same general form and tested the same basic areas.
- Name the element or symbol [Questions 1-2]
- generally very good results here
- Rewrite numbers using powers of ten [Question 4]
- Vocabulary (fill in the missing word) [question 5]
- results varied considerably
- Species and Sources associated with Air Pollution and Air Quality [Questions 3 and 6]
- many good answers but also many complete blanks
- many answers used familiar terms, but out of context (not really addressing the question)
- many answers combined familiar materials to produce bizarre concept (like CFC's are bad-- therefore toxic and breathing them is a serious health hazard.)
- many answers were extremely vague (to general to be a good answer)
Some thoughts....
- Some answers show that concepts aren't well understood
- for example, what is a mole?
- Some answers seem to show hurried answers-- picking a few ideas from the question (or answer) and not reading the whole item.
- Some answers show a poor grasp of basic materials
- for example, the people who guessed my height in kilograms or liters
- Many of the questions needed a careful look
- example: the isotope of sodium (we usually answer with # protons or # of neutrons, not an available answer)
- CO is toxic because it attaches to hemoglobin (as the answer suggests) but it does
not supply Oxygen
- Several Questions needed you to use the periodic table, but they don't say "look at the periodic table and tell me..."
- properties of sulfur
- Gallium (we never discussed it so you need a tool)
- Some questions require you to put together information and arrive at a plausible answer
- 32 C (the number is obviously deceptive, it's not 32 F)
- if 0 C=ice and 100 C= boiling, 32 C is in between so you can eliminate all but 1-2 answers
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