Match List I with List II and select the answer using the code...

Reaction A: $CaO(s) + H_2O(l) \rightarrow Ca(OH)_2(aq)$ is a combination reaction because two substances combine to form a single product. (A \rightarrow 3)

Reaction B: $CaCO_3(s) \rightarrow CaO(s) + CO_2(g)$ is a decomposition reaction because a single compound breaks down into two simpler substances upon heating. (B \rightarrow 4)

Reaction C: $Pb(s) + CuCl_2(aq) \rightarrow PbCl_2(aq) + Cu(s)$ is a single displacement reaction because lead displaces copper from the copper chloride solution. (C \rightarrow 1)

Reaction D: $Na_2SO_4(aq) + BaCl_2(aq) \rightarrow BaSO_4(s) + 2NaCl(aq)$ is a double displacement reaction because there is a mutual exchange of ions between the two reactants to form a precipitate. (D \rightarrow 2)

The correct matching is A-3, B-4, C-1, D-2.

Answer: A-3, B-4, C-1, D-2