"Whenever a stress is applied to a system at equilibrium, the equilibrium shifts in such a way so as to undo the effect of the stress imposed." This is the statement of

Options

A. Rate law
B. Law of mass action
C. Le-Chatelier principle
D. Dilution law

Explanation

To solve the question, we need to identify the principle that describes how a system at equilibrium responds to applied stress. Let's break down the solution step by step:

### Step-by-Step Solution:

1. **Understanding the Statement**: The statement provided indicates that when a stress is applied to a system at equilibrium, the system will adjust itself to counteract that stress. This is a fundamental concept in chemical equilibrium.

2. **Identifying the Type of Stress**: Stress can be in various forms such as changes in concentration, temperature, or pressure. The system will respond to these changes to restore a new equilibrium.

3. **Application of the Principle**: When a change is imposed on a system at equilibrium, the system will shift in a direction that reduces the effect of that change. For example, if pressure is increased, the equilibrium will shift to the side with fewer moles of gas to decrease the pressure.

4. **Recognizing the Principle**: The principle that describes this behavior is known as **Le Chatelier's Principle**. This principle states that if an external change (stress) is applied to a system at equilibrium, the system will adjust in such a way as to counteract that change.

5. **Conclusion**: Therefore, the statement given in the question is based on **Le Chatelier's Principle**.

### Final Answer:
The statement is based on **Le Chatelier's Principle**.

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