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Chemistry 100

Hour Exam 9/26/01

Part I -- Short Answers

(40 points total)

There were three versions of this section and the questions were different.

1. Write the symbol for the elements: (2 points each)

2. Write the name of the element with the symbol (2 points each)

3. Name three important processes that produce atmospheric SO₂ (sulfur dioxide) (12 points)

volcanos and geothermal vents
burning fuels with high sulfur content
- coal is the leading culprit
- petroleum can be a source (gasoline itself is very low sulfur)
some chemical processes such as metal refineries (Copper is the major example)
- vague answers like "cars", "factories" or "coal" won't get full credit. Catch all temrs like "polluters" won't get any credit

4. Write these numbers in power of ten notation (like 3.25 x 10-3)

5. Vocabulary (2 pts each)

a. Atoms with the same number of protons but different numbers of neutrons are said to
be _ ISOTOPES_ of the same element.
b. We live in the portion of the atmosphere that is called the _ TROPOSPHERE_.
c. The major process that removes CO₂ from the air is _ PHOTOSYNTHESIS__.

6. Two important processes that produce atmospheric nitrogen oxides are: (6 points)

lightning and electrical discharges (nature's way)
hot contact of N₂ and O₂ (air)
- occurs in gasoline engines, power plants, even fires
- Partial credit for nitrogen fixation by bacteria, legumes, termites (technically they don't form ntrogen oxides)
the process needs to be clearly identified-- a vague answer like "factories" , "fires" or "cars" isn't enough