Read the passage and answer the questions based on it. You are required to select your answers based on the contents of the passage and opinion of the author only. For many years, ship captains navigating the waters of Antarctica have been intrigued by sightings of emerald icebergs. Scientists have now explained their mystery. There, icebergs are turned upside down. Icebergs are blocks of ice that have broken off huge slabs of frozen snow called ice shelves. Their green appearance results from seawater that has frozen at the bottom over hundreds of years. The frozen sea water has dissolved organic matter which gives it a yellow tone and the fresh water ‘ice shelf’ above has a blue tinge. When the iceberg turns upside down, it appears green through the visual mix of yellow with the blue from below.
What are ice shelves?
They are huge pieces of chunks of ice.
Understanding Ice Shelves from the Passage
The question asks for the definition of ice shelves based on the provided passage. To answer this, we need to carefully read the passage and find where ice shelves are mentioned and described.
The passage states: "Icebergs are blocks of ice that have broken off huge slabs of frozen snow called ice shelves."
This sentence directly defines what ice shelves are in the context of the passage.
Analyzing the Options
Let's examine each option in light of the passage's definition:
- Option 1: They are huge pieces of chunks of ice.
- Option 2: They are frozen sea water.
- Option 3: They are pieces of ice which look like shelves.
- Option 4: They are huge pieces of ice which are very old.
Evaluating Each Option Against the Passage
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Option 1: The passage says ice shelves are "huge slabs of frozen snow". A slab is a large, flat piece. "Huge pieces of chunks of ice" aligns reasonably well with the idea of "huge slabs" composed of frozen snow (which is a form of ice). This definition focuses on the size and composition (ice/frozen snow).
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Option 2: The passage mentions frozen seawater giving the green colour to the bottom of icebergs, but it does not define ice shelves as being made of frozen seawater. Ice shelves are described as "huge slabs of frozen snow", which is fresh water ice.
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Option 3: The passage gives a technical definition based on their origin (where icebergs break off) and composition ("huge slabs of frozen snow"). It does not mention their appearance or state that they look like literal shelves. This option is not supported by the passage.
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Option 4: The passage mentions the frozen seawater layer at the bottom of icebergs can be "hundreds of years" old, contributing to the green colour. However, this age is attributed to a specific layer within the iceberg's origin point, not necessarily defining the entire ice shelf or stating that all ice shelves are defined solely by being "very old huge pieces of ice." The primary descriptive terms used for ice shelves are "huge slabs of frozen snow".
Conclusion Based on the Passage
Based on the direct statement in the passage, ice shelves are "huge slabs of frozen snow". Option 1, "They are huge pieces of chunks of ice," is the closest match provided among the options, describing them as large pieces of ice (frozen snow). The other options introduce concepts (frozen seawater composition, appearance resembling shelves, definition solely by age) that are either contradicted or not supported as the primary definition of ice shelves within this specific passage.
Revision Table: Key Concepts
| Concept | Definition/Description from Passage |
|---|---|
| Icebergs | Blocks of ice broken off ice shelves. |
| Ice Shelves | Huge slabs of frozen snow from which icebergs break off. |
| Green Icebergs | Result of inverted icebergs with frozen seawater bottoms containing dissolved organic matter (yellow) mixing visually with fresh water ice (blue). |
| Frozen Seawater | Found at the bottom of icebergs, contains dissolved organic matter, gives a yellow tone. Can be hundreds of years old. |
| Fresh Water Ice | Forms the main part of the ice shelf/iceberg, has a blue tinge. |
Additional Information: Types of Ice Formations
Understanding different types of ice formations in polar regions can be helpful. The passage discusses icebergs and ice shelves.
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Ice Sheets: Vast masses of glacial ice covering large land areas (like Antarctica or Greenland). Ice shelves are essentially floating extensions of ice sheets.
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Ice Shelves: Floating platforms of ice that form where ice sheets or glaciers flow down to the coast and onto the ocean surface. They are connected to the land ice.
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Icebergs: Large pieces of ice that have broken off from glaciers or ice shelves and drift in the open ocean. They are typically freshwater ice.
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Sea Ice: Ice formed by the freezing of seawater. It is much thinner than icebergs or ice shelves and does not originate from land ice.
The passage focuses on the relationship between ice shelves and icebergs, explaining icebergs come from ice shelves which are described as "huge slabs of frozen snow."
Similar Questions
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What are icebergs?
When the iceberg turns upside down, it appears ________.
The use of science in its simple form has helped man to ____________
Nature now needs to be protected from man because _____________
Forests are being destroyed in order to ________
The evil effect of destroying Nature instead of using it is seen in _________
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Important Questions from Reading Comprehension
What is the meaning of ‘intrigued’?
What are icebergs?
When the iceberg turns upside down, it appears ________.
The use of science in its simple form has helped man to ____________
Nature now needs to be protected from man because _____________
