Name

Sample Final (in-class)

Answers

Physical Science 101
Spring 1999

Note: This is only a sample of the in-class final. Please do not take the number of questions for each section as being indicative of the number of questions that will be asked.

SHORT ANSWER: Fill in the blank with the most appropriate word or short phrase.

DEFINITIONS: Provide a brief definition of the term in the space provided or on a separate sheet of paper.

2) Chemical reaction

Answer: A chemical bond involving the sharing of electrons between the atoms involved.

4) Molecular dipole

Answer: When the sum of all the charges in a molecule yields a net separation between positive and negative charges, this is called a dipole.

Answer: Rocks formed from the compaction and cementing of grains of previously existing rock.

Answer: Geologic period before the appearance of an abundant of fossils. Lasted from approximately 4.6-0.5 billion years ago.

Answer: Grouping of water droplets and/or ice crystals. Forms from rising, warm, moist air.

Answer: The name given to describe the domain in which all material things exist; three dimensions of space and one of time.

1) In relating theology and science, two «extremes» that are possible are extreme concordism and extreme separatism. What do these extremes describe? What are their strengths and weaknesses?

Answer: Strict concordism holds that every aspect of science must match with theology, i.e. that there cannot be any disagreement. Strict separatism sees the two fields as entirely distinct, with no interaction. Some strengths: For both viewpoints, it provides a clear-cut method for making decisions about the interaction of faith and science. Some weaknesses: For concordism, forcing the two fields to entirely match runs the risk of subordinating faith to science. For separatism, keeping the two fields entirely distinct runs the risk of theology holding to positions that are demonstrably false (e.g. geocentric vs. heliocentric solar system).

2) Why do we say electrons most affect an atom's size while protons and neutrons most affect an atom's mass?

Answer: Most of the mass of an atom is its nucleus. Each proton and neutron has a mass nearly 2000 times that of the mass of an electron. Electrons that surround the nucleus determine an atom's diameter. So electrons affect an atom's size and nucleons its mass.

3) Distinguish between nuclear fission and nuclear fusion. Which is a 20th century fuel and which will likely be a 21st century fuel?

Answer: Nuclear fission is the breaking apart of atomic nuclei into almost equal sized pieces. Nuclear fusion is the welding together of atomic nuclei. They are opposite processes. Nuclear fission has been powering nuclear plants for the second half of the 20th century. As this test question is being written, nuclear fusion is not yet practical, although it may be the fuel of choice in the 21st century.

4) Using the shell model of atomic structure, draw in the proper number and orientation of electrons (using arrows) for an oxygen atom (atomic number, 8).

Answer: You should have two paired arrows facing in opposite directions within the first shell and four paired electrons and two unpaired electrons in the second shell.

5) Distinguish between electron affinity and electronegativity.

Answer: Electronegativity and electron affinity are very similar concepts. Both refer to the attraction an atom has for electrons. Electronegativity, however, is more specific referring to the attraction an atom has for bonding electrons. Like electron affinity, electronegativity is greatest for the elements to the upper right of the periodic table and lowest for elements to the lower left. Noble gases are not considered in electronegativity discussions because, with only a few exceptions, they do not participate in chemical bonding.

6) Identify each of the substances in the following chemical reactions as acting as an "acid" or a "base."

PH 3 + H 2S Û PH 2 - + H 3S +

Answer: From left to right: acid, base, base, acid.

7) Relate silica content to fractional crystallization.

Answer: First of all fractional crystallization allows a single magma to generate several different igneous rocks. Minerals that have the highest melting points, which means those that have the lowest silica content, crystallize first, followed by minerals with lower melting points (those containing larger amounts of silica). As crystallization proceeds, the composition of the liquid in which the crystals form changes continuously. It becomes depleted in the constituents of minerals that have already crystallized and enriched in the constituents of minerals yet to crystallize, which acts to increase the silica content of the remaining liquid.

8) It is believed that large parts of the United States were once covered by shallow seas. What might be a reason for scientists to come to such a conclusion?

Answer: Marine fossils found in the interior of the continent. For example, recall the Guadalupe Mountains in Texas. The mountains are actually an ancient coral reef.

9) Why does air pressure decrease with height more rapidly in cold air than in warm air?

Answer: There are more air molecules per volume in cold air than in warm air; cold air is denser than warm air. As you move up a column of cold air, the densely packed air molecules yield a rapid change in pressure. In warmer, less dense air, because there are fewer molecules, air pressure does not decrease as rapidly.

10) What impact does the formation of the ozone layer have on our planet?

Answer: As a protective envelope, the formation of the ozone layer blocked most of the Sun's harmful ultraviolet radiation. Once this radiation was blocked, the Earth's surface became more hospitable to life.

11) What event marks the birth of a star, and what even marks its death?

Answer: A stellar body becomes a star when thermonuclear fusion is ignited in its core. Death occurs when its nuclear fires go out-when nuclear fusion ceases.