Session 1: Assessment

Assessment Questions for Session 1

Rank the following three permanent atmospheric gases by percent composition of the atmosphere (percent by volume of dry air) from greatest to least. State the permanent percentage of each gas.

Rank - Gas Percent
(by volume of dry air)

Nitrogen (N₂)

Argon (Ar)

Oxygen (O₂)

Complete the following sentence. Some gases are categorized as 'permanent' as opposed to variable because...

a) they do not vary even slightly from their present concentrations near the earth's surface as opposed to 'variable' gases which may vary as little as a fraction of a percent, as with ozone, to as much as 4%, as in the case of water vapor.

b) their concentrations are almost constant near the earth's surface.

c) though their atmospheric concentrations vary slightly, they never fall much below 1% (by volume of dry air) which suggests they are permanently present in the atmosphere.

Match the following:

SO₂	a) in the stratosphere this gas protects us from harmful ultraviolet rays, but in the lower troposphere, this gas is a primary component of photochemical smog
VOC's	b) often categorized by size, the can be very harmful when inhaled because they travel deep in to the lungs where they can accumulate over time
NO_x	c) commonly released by oil refineries, paper mills, and power plants, as well as naturally by volcanic eruptions, often associated with acid rain and fog
O₃	d) greenhouse gas, atmospheric concentrations rapidly rising due to the burning of fossil fuels
CFC's	e) includes CFC's and other hydrocarbons; primary sources include cleansers and refrigerants
CO₂	f) known to participate in the formation of smog; naturally released during bacterial action; anthropogenic sources include motor vehicles and waste disposal systems
Aerosols	g) responsible for the depletion of ozone in the stratosphere

Refer to the figure below and write the names of the layers indicated as A, B, C, D.

= A

= B

= C

= D

On to Session Critique

Back to Focus on Air Quality

Developed by

Rank - Gas	Percent (by volume of dry air)
Nitrogen (N₂)
Argon (Ar)
Oxygen (O₂)

	a) they do not vary even slightly from their present concentrations near the earth's surface as opposed to 'variable' gases which may vary as little as a fraction of a percent, as with ozone, to as much as 4%, as in the case of water vapor.
	b) their concentrations are almost constant near the earth's surface.
	c) though their atmospheric concentrations vary slightly, they never fall much below 1% (by volume of dry air) which suggests they are permanently present in the atmosphere.