Which term would you use to describe the material's ability to permanently change in shape?

• A. Plasticity
• B. Elasticity
• C. Ductility
• D. Hardness

Answer: (A)

Plasticity is the material's ability to permanently change shape when it is deformed beyond its elastic limit. When stress pushes the structure past the point where it would snap back to its original form, the atoms rearrange in a way that remains even after the load is removed. Elasticity, by contrast, is about temporary deformation that vanishes once the force is removed. Ductility describes how much plastic deformation a material can undergo before it breaks—often linked to being drawn into wires or thin sheets—while hardness concerns resistance to surface indentation and wear, not permanent shape change. So the term that best captures permanent shape change is plasticity.