Deck 5: Seawater

Question 1

The rule of constancy of composition of sea salts for open-ocean water specifies that regardless of the salinity, the major ions always appear in the same ratio to each other. 

Answer 1

True

Question 2

Cold seawater holds less oxygen than warm seawater at the same pressure and salinity.

Answer 2

False

Question 3

When the salinity of a seawater sample changes, the ratio of the major salt ions does not change.

Answer 3

True

Question 4

An ion with a negative charge is called an ________.

Question 5

In the process called osmosis, water naturally travels through a semipermeable membrane from the side of low salt concentration to the side of high salt concentration.

Question 6

The dissolving ability of water is related to

A) attraction between the water molecule's positive and negative charges and charges on other atoms.
B) its ability to form hydrogen bonds with other molecules.
C) its ability to transmit energy from water molecule to water molecule.
D) attraction between the water molecule's positive and negative charges and charges on other atoms and its ability to form hydrogen bonds with other molecules.
E) attraction between the water molecule's positive and negative charges and charges on other atoms, its ability to form hydrogen bonds with other molecules, and its ability to transmit energy from water molecule to water molecule.

Question 7

The relative molar abundance of carbon, nitrogen, and phosphorus in marine phytoplankton can be expressed in a relationship called the ________ ratio.

Question 8

The polar nature of water molecules aids in water's solvent abilities.

Question 9

The chemical constituents of sea salt that are not utilized or altered by biological processes are called nonconservative.

Question 10

Formation of evaporites acts to add salts to seawater.

Question 11

Carbon dioxide concentrations in seawater increase with depth.

Question 12

An ion with a positive charge is called a ________.

Question 13

Nutrients and dissolved gases in seawater are considered conservative substances.

Question 14

More oxygen is found in surface waters at lower latitudes than in surface waters at polar latitudes.

Question 15

Seawater percolating through the fractured crust along ridge systems acts to both remove salts from and add salts to seawater.

Question 16

Instruments used to measure the electrical conductivity of seawater can produce continuous readings of salinity with depth or continuous readings of salinity with time at a fixed depth.

Question 17

The process of reverse osmosis uses pressure to separate fresh water from salt water through a semipermeable membrane.

Question 18

Anoxic water contains too much oxygen.

Question 19

Salinity of seawater is approximately equal to the total dissolved salts in seawater expressed as grams of salt per kilogram of seawater.

Question 20

The salinity of a water sample can be determined by multiplying its ________ by 1.80655.

Question 21

Surface values of dissolved oxygen may exceed 100% saturation.

Question 22

Ions are removed from seawater most effectively by

A) evaporation.
B) freezing.
C) adsorption.
D) bacterial action.
E) None of these are correct; one method is not more effective than another.

Question 23

The average salinity of the oceans is about ______ parts per thousand (‰).

A) 30
B) 35
C) 37
D) 40
E) 45

Question 24

Acid rain falling on seawater has little effect on the pH of the oceans.

Question 25

Dittmar analyzed approximately seventy seawater samples collected around the world during the Challenger Expedition. He concluded that

A) seawater had the same salinity worldwide.
B) salt content changes due to processes that add or subtract salt.
C) the major ions were always present in the same ratios.
D) dissolved gases are always present in the same ratios.
E) the major ions were always present in the same ratios and dissolved gases are always present in the same ratios.

Question 26

Electrical conductivity readings at a known temperature measure

A) salinity.
B) temperature.
C) pressure.
D) viscosity.
E) density.

Question 27

Salinity may be measured by checking the water's

A) viscosity.
B) temperature.
C) conductivity.
D) pressure.
E) surface tension.

Question 28

Sources of the oceans' salts are believed to include

A) Earth's crust.
B) Earth's early atmosphere.
C) volcanic eruptions.
D) Earth's crust and Earth's early atmosphere.
E) Earth's crust, Earth's early atmosphere, and volcanic eruptions.

Question 29

The proportions of the major salts in seawater are constantly changing.

Question 30

If a chemical is not very abundant in the ocean but has a high rate of delivery to the ocean from land sources, it will have a __________ residence time in the ocean and will ________ become part of the seafloor sediments.

A) long; quickly
B) long; slowly
C) short; quickly
D) short; slowly
E) variable; variably

Question 31

The saturation value of oxygen in seawater increases as the temperature increases.

Question 32

The percentage of oxygen dissolved in seawater is greater in surface waters than in the deep ocean.

Question 33

If the salinity of ocean water is 36‰, there are ______g of salt left from evaporating 2kg of seawater.

A) 9
B) 18
C) 36
D) 54
E) 72

Question 34

The major ionic constituents of sea salt are normally found to

A) have a constant ratio of each constituent to each other.
B) behave as conservative materials.
C) have the same ratio to each other even when diluted by rainwater.
D) All of these are correct.
E) None of these are correct.

Question 35

An ion with a positive charge is known as a cation.

Question 36

The oceans are a major contributor of oxygen to the earth's atmosphere.

Question 37

Which situations cause an ion to have a long residence time in the oceans?

A) A high rate of ion addition
B) A rapid rate of reaction with other substances
C) Small total amount of ion present
D) A high rate of ion addition and a rapid rate of reaction with other substances acting together
E) None of these are correct.

Question 38

When salt-forming ions are placed in water they combine with each other and form solids.

Question 39

Surface salinities at high latitudes tend to be greater in summer than winter.

Question 40

An ion with a negative charge is a cation.

Question 41

Which desalination process requires the least energy?

A) Reverse osmosis
B) Distillation
C) Ion exchange
D) Freezing
E) Electrodialysis

Question 42

Carbon dioxide in seawater keeps the water's pH

A) slightly alkaline.
B) strongly alkaline.
C) slightly acid.
D) strongly acid.
E) neutral.

Question 43

The pH of seawater is regulated by

A) carbon dioxide.
B) oxygen.
C) temperature.
D) pressure.

Question 44

Which of these processes results in the transfer of the carbon from carbon dioxide to the deep sea?

A) Photosynthesis
B) Respiration
C) Decay
D) Photosynthesis and decay
E) Photosynthesis, respiration, and decay

Question 45

Electrodialysis produces ________ from low-salinity seawater.

A) bromine and magnesium
B) energy
C) fresh water
D) oxygen and carbon dioxide
E) table salt (sodium chloride)

Question 46

The residence time of an ion in the oceans may be determined by

A) multiplying the input rate by the output rate.
B) multiplying the total amount of the ion by either input or output rate.
C) dividing the total amount of the ion by either input or output rate.
D) dividing ionic concentration by input or output rate.
E) multiplying ionic concentration by total amount of the ion.

Question 47

Nutrients are non-conservative constituents of seawater because they

A) maintain constant ratios to each other.
B) do not maintain constant ratios to each other.
C) are recycled into plants and animals.
D) maintain constant ratios to each other and are recycled into plants and animals.
E) do not maintain constant ratios to each other and are recycled into plants and animals.

Question 48

Sources of oxygen in the open sea include

A) the atmosphere.
B) photosynthesis.
C) respiration and decay.
D) the atmosphere and photosynthesis.
E) photosynthesis and respiration and decay.

Question 49

Which ion has the shortest residence time in the oceans?

A) Chloride
B) Sodium
C) Potassium
D) Sulfate
E) Iron

Question 50

The total change in concentration of carbon dioxide with depth is small because

A) carbon dioxide combines with water to form carbonic acid and bicarbonate.
B) decay occurs at all depths.
C) photosynthesis occurs only at the surface.
D) carbon dioxide is added directly from the atmosphere.
E) carbon dioxide reacts with oxygen.

Question 51

A device used to separate fresh water from salt water using heat is called a(n)

A) osmometer.
B) dialysis machine.
C) still.
D) ion exchange column.
E) salt fountain.

Question 52

The depth at which the rate of photosynthesis balances the rate of plant respiration is known as the

A) saturation value depth.
B) compensation depth.
C) gas equilibrium depth.
D) photosynthesis cutoff depth.
E) None of these are correct.

Question 53

Which of the following ions has the highest concentration in seawater?

A) Na⁺
B) Cl^-
C) Mg²⁺
D) K⁺
E) Ca²⁺

Question 54

The concentration of carbon dioxide in surface water is low, whereas the concentration of oxygen is high because of the

A) difference in solubility of the gases.
B) exchange of gases between the atmosphere and the ocean.
C) photosynthesis process.
D) respiration of plants and animals.
E) conversion of carbon dioxide to bicarbonate.

Question 55

Trace elements in seawater are

A) toxic to marine life forms.
B) necessary for many marine life forms.
C) found in concentrations suitable for commercial use.
D) significant components of the total salt content of seawater.
E) in higher concentrations at lower salinities.

Question 56

Which of the following chemicals is commercially extracted from seawater?

A) Sulfur
B) Gold
C) Manganese
D) Bromine
E) Phosphate

Question 57

The rate at which the oceans absorb carbon dioxide is controlled by

A) temperature, salinity and pressure.
B) pH.
C) mixing and circulation processes.
D) temperature, salinity and pressure, pH, and mixing and circulation processes.

Question 58

Which latitudinal area tends to have the highest average surface salinity?

A) Polar areas (80^o to 90^o)
B) Equatorial areas (0^o-10^o)
C) Tropics (25^o-30^o)
D) Midlatitudes (60^o)
E) None of these are correct.

Question 59

Sea surface salinity is a function of _________ and __________.

Question 60

Which gas has the highest concentration throughout the entire ocean?

A) Oxygen
B) Carbon dioxide
C) Nitrogen
D) Argon
E) Concentrations vary with time

Question 61

Profiles of the concentration of oxygen and carbon dioxide in seawater from the surface to a depth of about 800 m are mirror images of each other.

Question 62

The residence time of iron and sodium in the oceans is approximately the same.

Question 63

The process of adherence of ions and molecules onto a particle's surface is called _______.

Question 64

Check each of the following constitutents of seawater that are conservative constituents.

Question 65

Carbon dioxide is added to seawater by

A) photosynthesis.
B) respiration.
C) decomposition.
D) transfer from the atmosphere.
E) respiration, decomposition and transfer from the atmosphere.

Question 66

The ratio of chlorine to sodium in seawater is about 1.8.

Question 67

In order to change the pH of water by one integer number (from 7 to 8 or from 8 to 7 for instance) you would have to change the concentration of the hydrogen ion by a factor of

A) 1000.
B) 500.
C) 100.
D) 50.
E) 10.

Question 68

The depth at which the rate of photosynthesis balances the rate of respiration is called the _______ depth.