The incorrect statement is:

Options

A. All the collisions between reactant molecules do not lead to a chemical change
B. A zero order reaction proceeds at a constant rate independent of concentration or time
C. Fast reactions have low activation energies
D. In a first order reaction, the reaction ideally takes finite time to be completed

Answer

To solve the question regarding which statement is incorrect, we will analyze each statement one by one.

### Step-by-Step Solution:

1. **Statement A**: "All the collisions between reactant molecules do not lead to a chemical change."
- **Analysis**: This statement is true. Not all collisions between molecules result in a chemical reaction. Only those collisions that occur with sufficient energy (threshold energy) and proper orientation can lead to a reaction.
- **Conclusion**: Statement A is true.

2. **Statement B**: "A zero-order reaction proceeds at a constant rate independent of concentration."
- **Analysis**: This statement is also true. In a zero-order reaction, the rate of reaction is constant and does not depend on the concentration of the reactants. The rate expression for a zero-order reaction is given by \( r = k \), where \( k \) is the rate constant.
- **Conclusion**: Statement B is true.

3. **Statement C**: "Fast reactions have low energies."
- **Analysis**: This statement is misleading. While catalysts can lower the activation energy and speed up reactions, it is not accurate to say that fast reactions inherently have low energies. The energy of the reactants and products can vary, and fast reactions can occur at high energy levels as well.
- **Conclusion**: Statement C is somewhat misleading but can be considered true in the context of catalysis.

4. **Statement D**: "In a first-order reaction, the reaction ideally takes finite time to complete."
- **Analysis**: This statement is incorrect. In a first-order reaction, the time taken to complete the reaction is theoretically infinite. The concentration of reactants decreases exponentially over time, but it never reaches zero in a finite amount of time.
- **Conclusion**: Statement D is false.

### Final Answer:
The incorrect statement is **Statement D**.