Question

Dissolving of a salt in water is considered a physical change while adding dilute sulphuric acid to
zinc is considered as a chemical change.
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Answer 1

dissolving process can be reversed, salt can be get back by evaporation process.

when sulphuric acid is added to zinc, there is a formation of zinc sulphate and hydrogen gas. which can not be separated by physical method. means irreversible change. means example

of chemical Change.

Answer 2

Explanation:

Dissolving salt in water is a physical change because it does not react with water and it will be in the form of hydrated ions like Na+(aq) and Cl-(aq). Therefore, no chemical reaction takes place.

NaCl + H2O ---> No reaction

But, in the case of adding dilute sulphuric acid to zinc, zinc reacts with sulphuric acid and forms zinc sulphate. So, addition of dilute sulphuric acid to zinc is a chemical change.

Zn + H2SO4 ---> ZnSO4 (ppt.)  + H2