Write the chemical equation of the reaction with an example each in which the following change has taken place:
(i) Change in colour
(ii) Change in temperature
(iii) Formation of precipitate.

Explanation

`Cu(s)+2AgNO_(3)(aq) to Cu(NO_(3))_(2)(aq)+2Ag`
The solution will become blue in colour and shiny silver metal will be deposite.
`NaOH+HCl to NaCl+H_(2)O+"Heat"`
Temperature will increase because heat is evolved.
`Pb(NO_(3))_(2)(aq)+2KI(aq) to PbI_(2)(s)+2KNO_(3)(aq)`
Yellow ppt
Yellow precipitate of `PbI_(2)` will be formed