$2 {\mathrm{KClO}}_3\to 2\mathrm{KCl} +3 {\mathrm{O}}_2\uparrow$ .This equation illustrates the law of

The given chemical reaction obeying law of “conservation of mass”. It means the mass of products and reactants to be equal.
$2{\mathrm{KClO}}_3\to 2\mathrm{KCl}+3{\mathrm{O}}_2\uparrow$. This equation illustrates the law of conservation of mass.