Correct Option
The correct option is Metallic lustre.
Explanation
Metals exhibit distinct physical properties in their pure state, which differentiate them from non-metals. These properties include hardness, sonority, and specific surface characteristics.
Option Analysis
- Metallic lustre is Correct: Metallic lustre refers to the property where metals, in their pure state, possess a shining surface. This characteristic shine is due to the interaction of light with the free electrons found in the metal lattice. Examples include Gold, Silver, and Copper.
- Ductility is Incorrect: Ductility is the ability of metals to be drawn into thin wires. Gold is the most ductile metal; for instance, a wire of about 2 km length can be drawn from one gram of gold.
- Malleability is Incorrect: Malleability is the property that allows metals to be beaten into thin sheets without breaking. Gold and Silver are the most malleable metals.
- Electrical conductivity is Incorrect: Electrical conductivity refers to the ability of a material to allow the flow of electric current. While metals are generally good conductors, this property is unrelated to their surface appearance.
Key Takeaway
Metallic lustre is the specific physical property describing the shining appearance of a metal's surface in its pure form.