Question

explain the similarity and different in two event namely adding NaOH to water and adding CaO to water

Answer 1

If we look at the analogy of adding NaOH and Cao to the water we find

 

Both are exothermic produces alkaline solution after a reaction.

 

The difference is that NaOH with water is physical reaction whereas Cao with water is a chemical reaction.

 

NaOh + H2O = Na+ + OH- ions whereas Cao + H2O = Ca (OH) 2