Which of the following is an example of a heterogeneous catalyst in the contact process for the manufacture of ${\text{H}}_2{\text{SO}}_4$?

Solution

1. The contact process involves the oxidation of ${\text{SO}}_2$ to ${\text{SO}}_3$.
2. The reaction is $2{\text{SO}}_2(g)+{\text{O}}_2(g)\stackrel{{\text{V}}_2{\text{O}}_5(s)}{\to }2{\text{SO}}_3(g)$.
3. Since the catalyst ${\text{V}}_2{\text{O}}_5$ is in the solid state and reactants are gases, it is heterogeneous.
4. Hence the answer is (A).