11.
Which of the following is a secondary pollutant

12.
The supersonic jets cause pollution by the thinning of

13.
Scientists are able to determine the air temperature in the thermosphere by:

14.
What is "Black Lung"?

15.
A permeable rock that contains hydrocarbon fluids and gases is called a/an

16.
In an oil trap formed by an anticline, __________ accumulates on top, __________ in the middle, and __________ at the bottom.

18.
Thermal belts are usually found

19.
The term "normal" refers to weather data averaged over:

20.
At any given time, ______ of the earth is illuminated by the sun.