Question

List any four changes around us through whose observing we can determine whether a chemical reaction has occurred or not?

Answer 1

1. Setting of milk to curd .
2. Rusting of Iron.
3. Fermentation of grapes.
4. Respiration.
5. Photosynthesis.

We can determine whether a chemical reaction has taken place or not by the following ways -
1. In a chemical reaction a new product is formed .
2. In a chemical reaction , chemical properties like odour , taste , colour of the substance changes

Answer 2

1. change in state
2. change in temp
3. change in colour
4. evolution of gas