* Calcium (Ca) is a metal.

* Carbon (C) is a non-metal.

* Trioxide (O₃) is a form of oxygen.

There are two possible interpretations of your question:

1. Calcium carbonate (CaCO₃): This is a common compound, also known as limestone. It is slightly soluble in water.

2. Calcium oxide (CaO): This is also known as quicklime and is soluble in water, reacting to form calcium hydroxide (Ca(OH)₂).

It's important to be precise with chemical names and formulas to avoid confusion.