Take-home Quiz #1 KEY

July 7, 2009
  1. [4 pts] A “natural” air pollutant is one that is found in nature. One example of this type of pollutant is _______________________ .

  2. [3 pts] What fundamental air pollution sink process can also be a source of air pollution? chemical reaction

  3. [6 pts] A photodissociation reaction occurs when a molecule absorbs electromagnetic radiation and subsequently breaks apart. If a molecule or atom just breaks apart by itself, without anything happening to it first (such as colliding with another molecule), we say that a spontaneous reaction occurred.

  4. [3 pts] The half-lifetime of substance A is greater than that of substance B if substance B is more likely to react away than substance A.

  5. [4 pts] Organic compounds must contain carbon and hydrogen.

  6. [6 pts] A molecule is made up of two or more atoms. The molecule is a compound, unless all of the parts making it up are of the same element. [second blank, NOT “substance”]

  7. [9 pts] The three size scales of air pollution are (smallest to largest) local, regional, global. For the smallest scale, an example of an air pollution problem of this size is __________.

  8. [6 pts] The layer of atmosphere that we are most concerned about polluting is the troposphere, because we have to live in it. The layer above that, called the stratosphere, contains the ozone layer, which we are also concerned about polluting since it protects us from harmful radiation from the Sun.

  9. [3 pts] The atmospheric pressure at any altitude is proportional to the weight of the atmosphere above that altitude; therefore, the pressure goes down as altitude increases.

  10. [6 pts] After the Earth formed but before it cooled, a secondary atmosphere formed. It consisted mostly of carbon dioxide and water vapor.

  11. [8 pts] During the evolution of the atmosphere, green plant photosynthesis, which was first performed by cyanobacteria, released oxygen into the Earth’s environment. However, this event led to the death of many of the anaerobic organisms, so this was an environmental pollution event as well as an important step in the evolution of life and the atmosphere.

  12. [6 pts] Some of the atmospheric nitrogen may have been directly outgassed from the Earth’s surface; however, most of it came from a process called denitrification, where oxides of nitrogen are released and later react away to eventually form molecular nitrogen.

  13. [4 pts] About 85% of the total atmospheric mass is located in the troposphere. This is because the atmospheric density decreases with increasing altitude, which concentrates the mass of the atmosphere in the lower layers. [anything in the range of 70-90% is acceptable for the first blank]

  14. [5 pts] The Sun and Earth are considered to be near-blackbodies. This means that the wavelengths at which the maximum emission of radiation occurs will be inversely proportional to their temperatures. It also means that the Sun will emit more radiation overall than the Earth because the Sun is hotter (and larger).

  15. [7 pts] In the steady-state box model formula, increasing source rate or residence time results in an increase in the steady-state concentration of the substance inside the box. However, increasing the volume results in the decrease of the steady-state concentration. [only parameters of the box model formula]

  16. [3 pts] In the steady-state box model, when the sink processes are made more efficient, the residence time goes down, which leads to a reduction in the steady-state concentration of the substance inside the box.

  17. [2 pts] In the box model, when the sink rate of a substance is greater than the source rate of that substance, the concentration of the substance in the box goes down.

  18. [3 pts] The fundamental dispersion processes are, from fastest to slowest, convection, turbulence, and molecular diffusion.

In-class Quiz #2 KEY

July 7, 2009

  1. [5 pts] The three most important types of electromagnetic radiation in sunlight are ultraviolet, visible, and infrared radiation. From Wien’s Law, the Sun emits mostly visible radiation, given its blackbody radiation temperature is 6000 K.

  2. [4 pts] The Earth’s first or primordial atmosphere consisted mostly of hydrogen and helium gases. This was replaced by a “secondary” atmosphere that was formed by a process called planetary outgassing.

  3. [4 pts] A meteor collison is thought to have created a global-scale cloud of dust and smoke that resulted in a sudden cooling of the Earth’s atmosphere and subsequent mass extinction of cold-blooded organisms. Evidence shows that this occurred about 65 million years ago.

  4. [8 pts.] The atmospheric temperature in the stratosphere goes up as altitude goes up because ozone in the upper part of the stratosphere absorbs ultraviolet radiation from the sunlight that passes through.

  5. [3 pts] These are the three most abundant “permanent” gases, in order from least to most abundant: argon, oxygen, nitrogen

  6. [6 pts] The atmospheric density goes down as altitude increases. This has the effect of causing collisional chemical reaction rates near the ground to be
    higher than at higher altitudes.