Statement (A): ${\mathrm{C}}_{\left(\mathrm{s}\right)}+{\mathrm{O}}_{2\left(\mathrm{g}\right)}\to {\mathrm{CO}}_{2\left(\mathrm{g}\right)}$ Follow law of chemical decomposition.

Statement (B): ${\mathrm{CaCO}}_{3\left(\mathrm{s}\right)}\stackrel{∆}{\to }{\mathrm{CaO}}_{\left(\mathrm{s}\right)}+{\mathrm{CO}}_{2\left(\mathrm{g}\right)}$ Follow law of chemical composition.

Statement (C): ${\mathrm{NaOH}}_{\left(\mathrm{aq}\right)}+{\mathrm{HCl}}_{\left(\mathrm{aq}\right)}\to {\mathrm{NaCl}}_{\left(\mathrm{aq}\right)}+{\mathrm{H}}_2{\mathrm{O}}_{\left(\mathrm{l}\right)}$ Follow law of chemical displacement

Chemical composition or Combination reaction means two or more individual reactants combined together to form a single compound.

$\mathrm{EX}: {\mathrm{C}}_{\left(\mathrm{s}\right)}+{\mathrm{O}}_{2\left(\mathrm{g}\right)}\to {\mathrm{CO}}_{2\left(\mathrm{g}\right)}$

During chemical decomposition, one compound can split into two or more substances upon heating.

${\mathrm{CaCO}}_{3\left(\mathrm{s}\right)}\stackrel{∆}{\to }{\mathrm{CaO}}_{\left(\mathrm{s}\right)}+{\mathrm{CO}}_{2\left(\mathrm{g}\right)}$

In chemical displacement reaction, high reactive element displaces low reactive element.

$\underset{\mathrm{Blue}}{{\mathrm{CuSO}}_{4\left(\mathrm{aq}\right)}}+{\mathrm{Fe}}_{\left(\mathrm{s}\right)}\to \underset{\mathrm{Green}}{{\mathrm{FeSO}}_{4\left(\mathrm{aq}\right)}}+{\mathrm{Cu}}_{\left(\mathrm{s}\right)}$