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Standard VII
Chemistry
Question

Chemical changes are _____ .
  1. always accompanied by exchange of light
  2. permanent, irreversible and a new substance is produced
  3. never accompanied by exchange of light and heat energy
  4. temporary, reversible and a new substance is produced

A
permanent, irreversible and a new substance is produced
B
always accompanied by exchange of light
C
temporary, reversible and a new substance is produced
D
never accompanied by exchange of light and heat energy
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Solution
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Chemical changes take place on the molecular level. A chemical change produces a new substance. It is a permanent and irreversible change.
Examples of chemical changes include combustion (burning), cooking an egg, rusting of an iron pan.

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