Q.Give two examples for zero order reaction.

Step 1. A zero order reaction has a rate that is independent of reactant concentration over a wide range -- genuinely rare, and usually arising when the rate-limiting step is something OTHER than a direct bimolecular collision (e.g. photon absorption, or a saturated catalyst surface).

Step 2. Example 1: the photochemical combination of hydrogen and chlorine, $H_2(g)+Cl_2(g)\xrightarrow{h\nu}2HCl(g)$ -- the rate is limited by how many photons are absorbed per second, not by the concentration of $H_2$ or $Cl_2$ present.

Step 3. Example 2: decomposition of nitrous oxide on a hot platinum surface, $N_2O(g)\rightleftharpoons N_2(g)+\tfrac{1}{2}O_2(g)$ -- once the platinum surface is fully saturated with adsorbed $N_2O$, adding more gas-phase $N_2O$ cannot speed the reaction up further, since only surface-bound molecules can react. …

Recall the book's listed zero order examples and state any …

• Citing the iodination-of-acetone example as fully 'zero order' without the qualifier -- it is zero order only WITH RESPECT TO IODINE, not zero order …