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Assertion : If we apply force to a lump ...

Assertion : If we apply force to a lump of putty or mud, they have no gross tendency to regain their previous shape.
Reason : This type of substances are called plastic substances.

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The correct Answer is:
To solve the question, we need to analyze both the assertion and the reason provided. ### Step-by-Step Solution: 1. **Understanding the Assertion**: - The assertion states that when a force is applied to a lump of putty or mud, they do not tend to regain their original shape after the force is removed. - This indicates that these materials undergo a permanent deformation when subjected to stress. 2. **Analyzing the Reason**: - The reason given is that such substances are classified as plastic substances. - Plastic substances are defined as materials that, when deformed, do not return to their original shape after the removal of the applied force. 3. **Connecting Assertion and Reason**: - The assertion is a specific observation about the behavior of putty and mud, while the reason provides a general classification of such behavior as plasticity. - Since the assertion correctly describes the behavior of putty and mud, and the reason explains why this behavior occurs (i.e., they are plastic substances), both statements are true. 4. **Conclusion**: - Since both the assertion and the reason are true, and the reason correctly explains the assertion, we conclude that the correct answer is that both the assertion and reason are true, and the reason is the correct explanation of the assertion. ### Final Answer: Both assertion and reason are true, and the reason is the correct explanation of the assertion.
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