Meher had two large chunks of coal. She set fire to the first chunk and broke the second one into pieces. Help Meher understand what kind of changes happened to the two chunks of coal at the end of the activity by choosing all the applicable statements.
- Both chunks of coal underwent physical changes only.
- The changes were reversible for the first chunk of coal only.
- Only physical changes took place for the second chunk of coal.
- Both chunks of coal underwent chemical changes only.
- The first case is an example of chemical changes.
Show answer & explanation
Correct answer: A
Explanation
The Correct Answer is option 1 i.e. Only C and E.
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C. Only physical changes took place for the second chunk of coal.
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Breaking coal into pieces is a physical change. The coal's composition remains unchanged; only its size and shape are altered. This change is reversible, as the pieces can be recombined into a whole.
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E. The first case is an example of chemical changes.
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Burning coal is a chemical change. Combustion transforms the coal into new substances like carbon dioxide and ash, releasing heat and light. This process is irreversible and involves a change in the chemical composition of the coal .
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Other Options:
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A. Both chunks of coal underwent physical changes only.
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Incorrect. While breaking the second chunk is a physical change, burning the first chunk is a chemical change.
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B. The changes were reversible for the first chunk of coal only.
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Incorrect. Burning coal is an irreversible chemical change; once burned, it cannot return to its original form.
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D. Both chunks of coal underwent chemical changes only.
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Incorrect. Only the first chunk underwent a chemical change; the second chunk underwent a physical change.
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