Which of the following reactions show(s) heterogeneous equilibria?

The equilibrium between water vapour and liquid water in a closed container is an example of heterogeneous equilibrium.H2O(l)⇌H2O(g)In this example, there is a gas phase and a liquid phase. In the same way, equilibrium between two solid phases and a gas phase, can be shown as,CaCO3(s)⇌ΔCaO(s)+CO2(g)