When the Quick lime [CaO] is added to the Water [H2O], it gives to the formation of Solid lime called Calcium Hydroxide [Ca(OH)2] by releasing large amount of Heat.

The Chemical Reaction is as below.

CaO(s) + H2O(l) → Ca(OH)2 (aq) + Heat↑.

How are you friends? Today I am telling you what happens when quick lime (Calcium Oxide) reacts with Water?
So let's start--

* When Quick lime (Calcium oxide) reacts with water it formed Slaked lime (Calcium hydroxide) and releasing a large amount of heat.It is also an example of Combination reaction.

CaO(s) + H2O(l) ---------Ca(OH)2(aq)+ Heat

This solution of Slaked lime is colourless produced by the reaction and is used for white washing walls.
Calcium hydroxide reacts slowly with the Carbon dioxide in air to form a thin layer of Calcium carbonate on the walls. Calcium carbonate is formed after two or three days of white washing and gives a shiny finish to the walls.
It is interesting to note that the chemical formula of marble is also CaCO3(s).

Ca(OH)2(aq) + CO2(g) ----------CaCO3(s)(Calcium carbonate) + H2O(l).

Friends I hope you understand it.
Thanks.