Take-home Quiz #1 KEY

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] Winds transport pollution into an area, so this is an air pollution source. They also act as an air pollution sink, through the fundamental sink process known as dispersion.
   
   
3. [3 pts] 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 larger than that of substance B if substance B is more likely to react away than substance A.
   
   
5. [7 pts] Organic compounds must contain carbon and hydrogen. A hydrocarbon can contain only those two substances.
   
   
6. [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 ____.
   
   
7. [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.
   
   
8. [5 pts] Within each of the following categories, list the gases in order from least to most abundant:
   the three most abundant permanent gases: argon, oxygen, nitrogen
   the two most abundant variable gases, on average: carbon dioxide, water vapor
   
   
9. [6 pts] After the Earth formed but before it cooled, a secondary atmosphere formed. It consisted mostly of water vapor and carbon dioxide.
   
   
10. [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.
    
    
11. [3 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.
    
    
12. [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, according to Wien’s Law. The Stefan-Boltzmann Law describes the relationship between the temperature of blackbodies and how much radiation they emit overall.
    
    
13. [6 pts] In the steady-state box model formula, increasing either the source rate or the residence time results in an increase in the steady-state concentration of the substance inside the box. [only parameters of the box model concentration formula]
    
    
14. [3 pts] The simplest way to reduce the concentration of air pollution in a “box” is to reduce the source rate.
    
    
15. [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.
    
    
16. [3 pts] The fundamental dispersion processes are, from fastest to slowest, convection, turbulence, and molecular diffusion.
    
    
17. [6 pts] The two physical constraints on an air parcel are:
    (a) the pressure inside and outside must be the same, and
    (b) mixing of air across the parcel boundary is not allowed.
    
    
18. [3 pts] To make an air parcel less dense and thus more buoyant, we can heat the air inside the parcel.