The reaction of acid, assuming HCl and calcium carbonate always produces a gas. The reaction is as follows:
2 HCl + CaCO3 --> CaCl2 + H2CO3
H2CO3, carbonic acid, is a weak acid that is unstable in water solutions at high concentrations. As such, it decomposes:
H2CO3 --> H2O + CO2
Then,
2 HCl + CaCO3 --> CaCl2 + H2O + CO2
The total ionic equation looks as follows:
2H+(aq) + 2 Cl-(aq) + CaCO3(s) --> Ca+2(aq) + 2 Cl-(aq) + H2O(l) + CO2(g)
Clearly, Cl- is a spectator ion as it is unchanged in the reaction. The net ionic reaction looks as follows:
2 H+(aq) + CaCO3(s) --> Ca+2(aq) + H2O(l) + CO2(g)
Gregor Mendel
Hope this helped !
The empirical formula of metal iodide : CoI₃(Cobalt(III) Iodide)
<h3>Further explanation</h3>
13.02 g sample of Cobalt , then mol Co(MW=58.933 g/mol) :

Mass of metal iodide formed : 97.12 g, so mass of Iodine :

Then mol iodine (MW=126.9045 g/mol) :

mol ratio of Cobalt and Iodine in the compound :