A student mixes aqueous solutions of Na2CO3 and CaCl2 and observes the formation of an insoluble white solid. Which of the following net ionic equations best accounts for the formation of the solid?
a) Ca2+(aq)+2Cl−(aq)→CaCl2(s)
b) Na2CO3(aq)+CaCl2(aq)→CaCO3(s)+2NaCl(aq)
c) Ca2+(aq)+CO32−(aq)→CaCO3(s)
d) 2Na+(aq)+CO32−(aq)→Na2CO3(s)