Identify the correct order of steps in heterogeneous catalysis.
(i) Adsorption of reactant molecules on the surface of the catalyst.
(ii) Diffusion of reactant to the surface of the catalyst.
(iii) Formation of reactions product on the catalyst surface.
(iv) Diffusion of reactions product from the catalyst surface.
(v) Formation of activated intermediate.

Options

A. (ii), (i), (v) , (iii), (iv)
B. (ii), (i), (iii), (iv), (v)
C. (iii), (i), (ii), (iv), (v)
D. (iii), (i), (ii), (v), (iv)

Answer

To identify the correct order of steps in heterogeneous catalysis, we will analyze the given steps and arrange them logically based on the process of heterogeneous catalysis.

### Step-by-Step Solution:

1. **Diffusion of reactants to the surface of the catalyst (ii)**:
- The first step in heterogeneous catalysis is the diffusion of reactant molecules from the bulk phase to the surface of the catalyst. This is essential for the reaction to occur since the reactants need to be in contact with the catalyst.

2. **Adsorption of reactant molecules on the surface of the catalyst (i)**:
- Once the reactants have diffused to the surface, the next step is their adsorption onto the catalyst surface. This involves the formation of weak interactions between the reactant molecules and the catalyst.

3. **Formation of activated intermediate (v)**:
- After adsorption, the reactant molecules undergo a transformation to form activated intermediates. This is a crucial step where the reactants are converted into a more reactive form.

4. **Formation of reaction products on the catalyst surface (iii)**:
- Following the formation of activated intermediates, the next step is the actual reaction that leads to the formation of products on the catalyst surface.

5. **Diffusion of reaction products from the catalyst surface (iv)**:
- Finally, the reaction products must diffuse away from the catalyst surface into the bulk phase, allowing the catalyst to be available for further reactions.

### Correct Order:
Thus, the correct order of steps in heterogeneous catalysis is:
- (ii) Diffusion of reactants to the surface of the catalyst
- (i) Adsorption of reactant molecules on the surface of the catalyst
- (v) Formation of activated intermediate
- (iii) Formation of reaction products on the catalyst surface
- (iv) Diffusion of reaction products from the catalyst surface

In numerical form, this is represented as: **2, 1, 5, 3, 4**.