The property of a material which enables it to retain the deformation permanently, is called:
🔬 Understanding Elastic vs. Plastic Deformation
When a force is applied to a material, it deforms. The way it deforms can be categorized into two fundamental types, which is the core of this question.
Elastic Deformation: This is a temporary change in shape. The material returns to its original dimensions after the force is removed. Think of stretching a rubber band and letting it go.
Plastic Deformation: This is a permanent, non-reversible change in shape. The material does not return to its original dimensions after the force is removed. Think of bending a paperclip; it stays bent.
⚖️ Detailed Analysis of the Options
The question asks for the property that allows a material to "retain the deformation permanently." This is the definition of plastic deformation, so we need to find the term that describes this ability.
(d) Plasticity
Definition: This is the general term for the ability of a solid material to undergo permanent deformation when a load is applied. It is the property that allows materials to be shaped, formed, and molded.
Conclusion: This is the correct and most general term for the phenomenon described.
(a) Brittleness
Definition: This is the tendency of a material to fracture with very little or no plastic deformation. It is the opposite of plasticity. A brittle material breaks before it permanently changes shape.
Conclusion: Incorrect.
(b) Ductility & (c) Malleability
Definition: These are two specific *types* of plasticity.
• Ductility is plasticity under tensile stress (allowing it to be drawn into wires).
• Malleability is plasticity under compressive stress (allowing it to be hammered into sheets).
Conclusion: While both are forms of permanent deformation, Plasticity is the broader, more fundamental property that encompasses both. Therefore, Plasticity is the best and most general answer.
💡 Study Tips for Material Properties
- Plastic = Permanent: The easiest way to remember is that "Plastic" deformation is "Permanent."
- Elastic = Snaps Back: Elastic deformation is temporary, like an elastic band.
- Plasticity is the Parent: Think of Plasticity as the parent category. Ductility and Malleability are its two children, describing specific ways a material can be permanently deformed.