how is lime(CaO) formed and give its uses

Formation:

Calcium oxide is usually made by the thermal decomposition of materials such as limestone, that contain calcium carbonate (CaCO₃; mineral name: calcite) in a lime kiln. This is accomplished by heating the material to above 825°C,a process called calcination or lime-burning, to liberate a molecule of carbon dioxide (CO₂); leaving CaO.

Uses:

It is used in mortar and plaster to increase the rate of hardening as well as to improve adhesion.It is also used in water and sewage treatment to reduce acidity, to soften, as a flocculant, and to remove phosphates and other impurities; in agriculture to improve acidic soils; and in pollution control.