Cambridge IGCSE · Marine Science (0697)

Dissolved gases: Practice Questions

5 multiple-choice questions marked as you go, and 5 written questions with worked solutions. All on Dissolved gases.

10 questions23 marksFree, no account

Question 1

1 mark

Which statement accurately describes the solubility of oxygen gas from the atmosphere when it dissolves in sea water?

Question 2

1 mark

A marine researcher observes that the surface waters of the Arctic Ocean typically have a much higher concentration of dissolved oxygen than the surface waters of the tropical Caribbean Sea. Which of the following provides the best scientific explanation for this observation?

Question 3

1 mark

In the open ocean, the concentration of dissolved oxygen often reaches a minimum at depths between \(200\text{ m}\) and \(1000\text{ m}\) (the twilight zone). What is the primary reason for this oxygen minimum?

Question 4

1 mark

According to the syllabus, how is the solubility of oxygen described when it dissolves from the atmosphere into sea water?

Question 5

1 mark

How does the concentration of dissolved oxygen typically change from the twilight zone (\(200\text{--}1000\text{ m}\)) to the midnight zone (below \(1000\text{ m}\))?

Question 6

2 marks

State the effect of a decrease in sea water temperature on the solubility of atmospheric gases like oxygen.

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Question 7

3 marks

Compare the relative concentrations of oxygen and carbon dioxide in the atmosphere with their concentrations when dissolved in sea water.

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Question 8

6 marks

Describe the vertical distribution of dissolved oxygen from the ocean surface down to the midnight zone, and explain the primary reason for the oxygen minimum layer.

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Question 9

3 marks

Gases from the atmosphere dissolve in sea water and play a critical role in marine ecosystems.

(a) Identify two primary gases that dissolve from the Earth's atmosphere into the surface of the ocean.
(b) State how an increase in sea water temperature affects the solubility of oxygen.
(c) Name one biological process in marine organisms that produces carbon dioxide as a byproduct.

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Question 10

4 marks

Gases such as oxygen and carbon dioxide from the atmosphere dissolve into sea water and are essential for marine life.
(a) State which of these two gases, oxygen or carbon dioxide, has a lower solubility in sea water.
(b) Use particle theory to explain why an increase in the temperature of sea water reduces the solubility of dissolved oxygen.

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