Here's the breakdown:

* Ca(OH)₂: This represents the chemical formula for calcium hydroxide itself.

* (aq): This abbreviation stands for "aqueous," indicating that the calcium hydroxide is dissolved in water.

In an aqueous solution, calcium hydroxide dissociates into its ions:

Ca(OH)₂(aq) → Ca²⁺(aq) + 2OH⁻(aq)