Question

1. Define chemical reaction. State four observations which helps us to determine that chemical reaction has taken place. write one example of each observation with a balanced chemical equation.​

Answer 1

The process in which old bonds break and new bonds formed are known as chemical reaction...

There are six observations which helps us to determine that chemical reaction has taken place ....

The observations r as follows:

1) change in colour takes place ..

for example - when citric acid is added to pottasium permangante which is colourless then its colour chnges into pink...

2) change in odour - when alcohol is added to ester in the presence of mineral acid then it gaves the smell of fruity ester...

3)change in temperature- heat is released or liberated...

4) change in state- hydrogen + oxygen = water

5)evolution of gases

6) formation of precipitate

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