which of the following reations are examples for heterogeneous catalysis ?

Options

A. `2H_(2)O_(2)(l)overset(MnO_(2)(s))to2H_(2)O(l)+O_(2)(g)`
B. `2SO_(2)(g)+ O_(2)(g)overset(NO(g))to 2SO_(3)(g)`
C. `2SO_(2)(g)+ O_(2)(g)overset(NO(g))to 2SO_(3)(g)`
D. `CH_(3)COOC_(2)H_(5)(aq)+H_(2)O(l)overset(HCl(aq))toCH_(3)COOH(aq.)+ C_(2)H_(5)OH(aq.)`

Answer

To determine which reactions are examples of heterogeneous catalysis, we need to understand the definition and characteristics of heterogeneous catalysis.

### Step-by-Step Solution:

1. **Definition of Heterogeneous Catalysis**:
- Heterogeneous catalysis occurs when the reactants and the catalyst are in different physical states (phases). For example, a solid catalyst can facilitate a reaction between gaseous or liquid reactants.

2. **Identify the Physical States**:
- Examine the physical states of the reactants and the catalysts in the given reactions. The states can be solid, liquid, or gas.

3. **Analyze Each Reaction**:
- **Reaction 1**: If the reactants are in liquid form and the catalyst is solid, this is an example of heterogeneous catalysis.
- **Reaction 2**: If both reactants are gases and the catalyst is also a gas, this is not heterogeneous; it is homogeneous catalysis.
- **Reaction 3**: If one reactant is a gas and the other is a solid, this is an example of heterogeneous catalysis.
- **Reaction 4**: If both reactants are in the same phase (e.g., both are liquids or both are gases), this is also not heterogeneous; it is homogeneous catalysis.

4. **Conclusion**:
- Based on the analysis, identify which reactions fit the criteria for heterogeneous catalysis. The reactions where the catalyst and at least one reactant are in different physical states are examples of heterogeneous catalysis.

### Final Answer:
- The reactions that are examples of heterogeneous catalysis are those where the catalyst is in a different phase than the reactants, such as:
- A solid catalyst with liquid or gaseous reactants.
- A solid catalyst with gaseous reactants.