Hey there!:
As per solubility rules inorganic compounds that are soluble are
:Ammonium (NH4⁺),potassium (K⁺), sodium (Na⁺) : All ammonium, potassium and sodium salts are soluble. Exceptions:some transition metal compounds.
Bromides (Br⁻), chlorides (Cl⁻) and iodides (I⁻): Most bromides are soluble. Exceptions: salts containing silver, lead, and mercury.
So Rb2Cl2 is expected to be soluble.
As per solubility rules inorganic compounds that are insoluble are : Carbonates (CO₃²⁻), chromates (CrO₄²⁻), phosphates (PO₄³⁻), silicates (SiO₄²⁻): All carbonates, chromates, phosphates and silicates are insoluble. Exceptions: those of ammonium, potassium and sodium.
So CaCO3 is insoluble and precipitates
Therefore:
The completed equation is :
Rb2CO3(aq) + CaCl2(aq) → CaCO3(s) + Rb2Cl2(aq)
Hope that helps!