What type of chemical reaction is represented by the following equation?
$\mathrm{A}+\mathrm{BC}\to \mathrm{AC}+\mathrm{B}$

(Displacement reaction/Decomposition reaction/Combination reaction)

$\mathrm{A}+\mathrm{B}\to \mathrm{C}$

$\mathrm{PQ}+\mathrm{RS}\to \mathrm{PS}+\mathrm{RQ}$

Balance the following chemical equation:

${\mathrm{FeSO}}_4\stackrel{\mathrm{Heat}}{\to }{\mathrm{Fe}}_2{\mathrm{O}}_3+{\mathrm{SO}}_2+{\mathrm{SO}}_3$

Balance the following chemical equation:

$\mathrm{Pb}{\left({\mathrm{NO}}_3\right)}_2\left(\mathrm{s}\right) \stackrel{\mathrm{heat}}{\to } \mathrm{PbO}\left(\mathrm{s}\right)+{\mathrm{NO}}_2\left(\mathrm{g}\right)+{\mathrm{O}}_2\left(\mathrm{g}\right)$

What type of reaction is represented by the following equation?

$\mathrm{CaO}+{\mathrm{CO}}_2\to {\mathrm{CaCO}}_3$ (Decomposition reaction/ Combination reaction)