16. The groundwater can become confined between two impermeable layers. This type of enclosed water is called
A. artesian
B. artesian well
C. unconfined groundwater
D. confined groundwater
17. The largest glaciers are
A. mountain glaciers
B. alpine glaciers
C. continental glaciers
D. piedmont glaciers
18. The ionosphere includes
A. mesosphere
B. thermosphere
C. thermosphere and exosphere
D. thermosphere, exosphere and mesosphere
19. The highest degree of concentration of mineral deposits are found in
A. northeastern zone
B. northwestern zone
C. southern zone
D. All of the above
20. The group of minerals chemically containing hydrocarbons is
A. silicate group
B. organic group
C. oxide group
D. hydride group