Give four examples of heterogeneous catalysis.

(N/A) $(i)$ Oxidation of sulphur dioxide to form sulphur trioxide. In this reaction,$Pt$ acts as a catalyst.
$2SO_{2(g)} + O_{2(g)} \xrightarrow{Pt(s)} 2SO_{3(g)}$
$(ii)$ Formation of ammonia by the combination of dinitrogen and dihydrogen in the presence of finely divided iron $(Fe)$.
$N_{2(g)} + 3H_{2(g)} \xrightarrow{Fe(s)} 2NH_{3(g)}$
This process is called the Haber's process.
$(iii)$ Ostwald's process: Oxidation of ammonia to nitric oxide in the presence of platinum $(Pt)$.
$4NH_{3(g)} + 5O_{2(g)} \xrightarrow{Pt(s)} 4NO_{(g)} + 6H_{2}O_{(g)}$
$(iv)$ Hydrogenation of vegetable oils in the presence of nickel $(Ni)$.
$\text{Vegetable oil}_{(l)} + H_{2(g)} \xrightarrow{Ni(s)} \text{Vegetable ghee}_{(s)}$