Give two examples for zero Order reactions.

1) All photo chemical reactions and enzyme catalyzed reactions are zero order reactions.
$\text{ 2) }2\mathrm{HI}\stackrel{\mathrm{Au}}{\to }{\mathrm{H}}_2+{\mathrm{I}}_2$
(decomposition of HI)
$\text{ 3) }2{\mathrm{NH}}_{3\left(\mathrm{g}\right)}\stackrel{\mathrm{Pt},1130\mathrm{k}}{\to }{\mathrm{N}}_{2\left(\mathrm{g}\right)}+3{\mathrm{H}}_{2\left(\mathrm{g}\right)}$
Zero order reaction: The Rate of reaction is directly proportional to zero power of concentration reactant in a chemical reaction.