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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 pts each)

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

3. Name two important processes that produce atmospheric NO and NO₂ (nitrogen oxides) (8 pts)

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

4. Write these numbers in power of ten notation (2 pts each)

5. Vocabulary (2 pts each)

a. Atoms with the same number of protons but different numbers of neutrons are said t be __ISOTOPES__ of the same element.
b. The portion of the atmosphere containing the ozone layer is called the _STRATOSPHERE. (It is an upper layer, but that's not the name)
c. The major process that removes CO₂ from the air is PHOTOSYNTHESIS_.

6. Define a fossil fuel and give two examples: (10 points)

A fossil fuel, defined, needs to address "fossil"
Material derived from plant/animal material deposited under the earth long time ago.
Now used as a fuel (or as a source of chemicals)
- petroleum
- coal
- peat
- natural gas