Chemical Engineering - Materials and Construction - Discussion

Malleability:
Malleability is the property by virtue of which a material may be hammered or rolled into thin sheets without rupture. This property generally increases with the increase of temperature. Malleability is the ability of a metal to exhibit large deformation or plastic response when being subjected to compressive force. Lead, soft steel, wrought iron, copper and aluminum are some materials in order of diminishing malleability.

Ductility:
Ductility is the property of the material that enables it to be drawn out or elongated to an appreciable extent before rupture occurs. The percentage elongation or percentage reduction in the area before rupture of a test specimen is the measure of ductility. Normally if the percentage elongation exceeds 15% the material is ductile and if it is less than 5% the material is brittle. Lead, copper, aluminium, and mild steel are typical ductile materials.

Brittleness:
Brittleness is opposite to ductility. Brittle materials show little deformation before fracture and failure occurs suddenly without any warning i.e. it is the property of breaking without much permanent distortion. Normally if the elongation is less than 5% the material is brittle.
E.G. Cast iron, glass, and ceramics are typical brittle materials.

Lead is minimum malleabile material out of these four.

Descending order of the list of the highest medals of malleability
1. Gold
2. Silver
3. Aluminium
4. Copper
5. Tin
6. Lead
7. Zinc
8. Iron

Out of the given options, Aluminium is most malleable. Option (C) should be correct.