Collision theory is applicable to

Options

A. First order reactions
B. Zero order reactions
C. Bimolecular reactions
D. Intermolecular reactions

Answer

### Step-by-Step Solution:

1. **Understanding Collision Theory**:
- Collision theory is a model that helps explain how chemical reactions occur and why reaction rates differ for different reactions. It is based on the idea that for a reaction to take place, reactant particles must collide with sufficient energy and proper orientation.

2. **Key Assumptions of Collision Theory**:
- The theory assumes that:
- Reactant particles (atoms or molecules) must collide.
- The collisions must occur with enough energy to overcome the activation energy barrier.
- The orientation of the colliding particles must be favorable for the reaction to occur.

3. **Types of Reactions**:
- Reactions can be classified based on the number of reactant particles involved:
- **Unimolecular Reactions**: Involve one reactant particle (not applicable for collision theory).
- **Bimolecular Reactions**: Involve two reactant particles colliding (applicable for collision theory).
- **Termolecular Reactions**: Involve three reactant particles colliding (less common and more complex).

4. **Conclusion**:
- Collision theory is primarily applicable to bimolecular reactions, where at least two species must collide for a reaction to occur. Therefore, it is not applicable to zero-order or first-order reactions, as these do not require collisions between two reactant species.

### Final Answer:
Collision theory is applicable to bimolecular reactions.

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