Here's why:

* Limewater is a saturated solution of calcium hydroxide (Ca(OH)₂).

* Calcium hydroxide is a strong base. This means it readily releases hydroxide ions (OH-) into solution.

* The presence of hydroxide ions (OH-) makes the solution alkaline (basic).

Limewater is used in various applications because of its basic nature. For example, it's used in the production of mortar and cement, and also as an antacid.