Identify the compound that is the main component of the limescale deposit in a kettle used in hard water area. - Leaving Cert Chemistry - Question (i) - 2020

The main compound that constitutes limescale deposits in kettles, particularly in hard water areas, is calcium carbonate, represented as CaCO₃. This compound accumulates due to the precipitation of dissolved calcium ions when water is heated.

In some instances, magnesium carbonate (MgCO₃) may also contribute to the limescale, though calcium carbonate is typically the primary component.