In-class quiz #3

1. [6 pts.] Absorption of infrared radiation by water vapor and carbon dioxide helps make the surface of the Earth habitable for life. Both of these gases are classified as variable gases, since their mixing ratios can change over relatively short periods of time.
   
   
2. [5 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.
   
   
3. [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.
   
   
4. [4 pts] A meteor collision on Earth 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.
   
   
5. [5 pts.] When the source rate of a pollutant is greater than the sink rate of the pollutant, the concentration of the pollutant in a box will increase over time. In order for the concentration to be constant over time, these parameters must be equal to each other.
   
   
6. [6 pts.] Using box model concepts, we can reduce the concentration of air pollution inside a box by: (i) reducing the source rate; (ii) reducing the residence time; or (iii) increasing the box's volume.