Question

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Question number 5 only question number 5 (five)

Answer 1

Answer:

The four changes which tell that a chemical reaction has taken place are:

1. Color change

2. Evolution of gases

3. Change of state

4. Presence of precipitate

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Answer 2

Explanation:

1)Change in colour

2)Change in concentration

3)Increase or decrease in temperature

4)change in ph

these may help us to determine whether a chemical reaction have taken place or not

Hope it will help you.