The reaction, A + B `to` P can never be

Options

A. Second order reaction
B. First order reaction
C. Unimolecular reaction
D. zero order reaction

Answer

To determine which type of reaction the equation A + B → P can never be, we need to analyze the nature of the reaction based on the number of reactants involved.

### Step-by-Step Solution:

1. **Identify the Reaction Type**: The given reaction is A + B → P. Here, two reactants (A and B) are involved in producing a product (P).

2. **Understand Molecularity**: Molecularity refers to the number of reactant molecules involved in an elementary reaction. It can be classified as:
- **Unimolecular**: Involves one reactant molecule.
- **Bimolecular**: Involves two reactant molecules.
- **Termolecular**: Involves three reactant molecules.

3. **Analyze the Given Reaction**: Since the reaction involves two reactants (A and B), it cannot be classified as unimolecular because unimolecular reactions only involve a single reactant.

4. **Conclusion**: Therefore, the reaction A + B → P can never be unimolecular. The correct option is that the reaction cannot be unimolecular.

### Final Answer:
The reaction A + B → P can never be unimolecular.