Earth Science: Geology, the Environment, and the Universe

Section 2: Seawater

Seawater

1
The salinity of seawater is __________ over geologic time.
A)increasing
B)decreasing
C)constant
D)always changing
2
What is the densest and coldest water mass of all Earth's oceans?
A)North Atlantic deep water
B)Antarctic intermediate water
C)Antarctic bottom water
D)Gulf Stream
3
What is the cause of ocean layering?
A)evaporation
B)density differences
C)polar ice caps
D)currents
4
Why are salinities lower than average in some areas close to the equator?
A)rapid evaporation
B)abundant precipitation
C)larger clouds
D)stronger winds
5
According to the graph, which salt is the most abundant in sea water?
sodium chloride (NaCl) 23.48 g
magnesium chloride (MgCl2)4.98 g
sodium sulphate(Na2SO4)3.92 g
calcium chloride (CaCl2)1.10 g
potassium chloride (KCl )0.66 g
sodium nicarbonate (NaHCO3)0.19 g
potassium bromide (KBr)0.10 g

A)potassium bromide
B)sodium chloride
C)sodium sulfate
D)magnesium chloride
6
What layer is shown right above the thermocline (around 1000 meters deep) in the graph?
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A)surface layer
B)top layer
C)thermal layer
D)bottom layer
7
Which element is not an ion found in ocean water?
A)Cl
B)Na
C)K
D)Ni
8
The density of seawater is dependent on __________.
A)salinity and temperature
B)temperature and currents
C)salinity only
D)temperature only
9
What is the average salinity of ocean water?
A)37 percent
B)37 ppt
C)30 ppt
D)35 ppt
10
What is the thermocline?
A)the formation of cold water coming from Antarctica
B)a layer of cold water in the ocean
C)a transitional layer in the ocean where temperature decreases rapidly with depth
D)a change in salinity with depth
11
The map shows the different surface temperatures of ocean water around the globe in degrees Celsius. What causes the band of 29-32 °C?
Click here for figure (41.0K)
A)This is where the most volcanic activity takes place.
B)It receives the most direct sunlight throughout the year.
C)The ocean currents don't move the warm water around.
D)This has the highest concentration of salt.
12
What is one source of sodium ions found in the ocean?
A)the shells of marine organisms
B)volcanic gases
C)ultraviolet radiation
D)evaporation
13
In the graph, what is the sharp drop in temperature from about 20°C to about 7 °C called?
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A)the temperaturcline
B)the trophocline
C)the thermocline
D)the tomocline
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