Question

Shiny finish appears on the walls after two-thirds days of white washing.

Answer 1

Slaked lime is prepared by adding water to quick lime.
A solution of slaked lime (Ca(OH)2) is used to white wash the walls.Calcium hydroxide reacts with the carbon dioxide in air to form thin layer of calcium carbonate on the walls. It gives a shiny finish to the walls.

Answer 2

the shiny layer is of calcium carbonate..
CaCO3...
thank you hope it helps...