Whenever a reaction between an oxidising agent and a reducing agent is carried out, a compound of lower oxidation state is formed if the reducing agent is in excess and a compound of higher oxidation state is formed if the oxidising agent is in excess. Justify this statement giving three illustrations.

Explanation

To justify the statement that a compound of lower oxidation state is formed when the reducing agent is in excess, and a compound of higher oxidation state is formed when the oxidizing agent is in excess, we can illustrate this with three examples:

### Example 1: Reaction between Phosphorus and Fluorine

1. **Identify the Reactants**: We have phosphorus (P) and fluorine (F).
2. **Determine the Role of Each Reactant**: Fluorine acts as the oxidizing agent, while phosphorus acts as the reducing agent.
3. **Case 1 - Reducing Agent in Excess**:
- When phosphorus is in excess, the reaction produces phosphorus trifluoride (PF3).
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