Allotropy (polymorphism): definition based on crystal structure changes with temperature Identify the correct statement describing an allotropic material. Choose the correct description.
Mechanical Engineering
Engineering Materials
Difficulty: Easy
Choose an option
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AHas a fixed crystal structure at all temperatures
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BHas atoms distributed in a random (amorphous) pattern
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CExhibits different crystal structures at different temperatures
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DAny one of the above
Answer
Correct Answer: Exhibits different crystal structures at different temperatures
Explanation
ConceptAllotropy (polymorphism in metals) is the ability of a material (e.g., iron, carbon as graphite/diamond) to exist in more than one crystal structure depending on temperature (and sometimes pressure/composition).
Eliminate options(a) contradicts allotropy; (b) describes amorphous solids, not crystalline allotropes; (d) is incorrect because only (c) is true for allotropy.
Final AnswerExhibits different crystal structures at different temperatures