Question

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How do we say that in any change there is chemical reaction takes place or not? ​

Answer 1

Answer:

The following can indicate that a chemical change has taken place, although this evidence is not conclusive: Change of odor. Change of color (for example, silver to reddish-brown when iron rusts). Change in temperature or energy, such as the production (exothermic) or loss (endothermic) of heat.

Answer 2

Answer:

change of odours,change of colour