Question

How do we know that -a chemical -reaction has take place?​

Answer 1

• a change that change state and colour of substance
• a change that release heat energy
• change which forms and in soluble substance as predicate
• a change that liberates a gas .

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Answer 2

Answer:

A chemical reaction takes place if :

1) there is change in colour

2)change in odour

3)change in temperature

4) evolution of gas

5)formation of precipitate