Malleability from mobile ion layers in metals

Steps:

• Metals consist of a lattice of positive ions surrounded by delocalized electrons.
• Malleability allows metals to be hammered into shapes because layers of positive ions slide over each other.
• The delocalized electrons maintain bonding as ions move, preventing fracture.
• Electrical conductivity occurs via free movement of delocalized electrons, not ions.

Why A is correct:

• Malleability specifically results from the ability of positive ion layers to shift under stress while delocalized electrons hold the structure together (metallic bonding definition).

Why the others are wrong:

• B: Electrical conductivity relies on delocalized electrons carrying charge, not ion movement.
• C: Includes conductivity, which is electron-based, not ion layer sliding.
• D: Ignores that malleability directly stems from mobile ion layers.

Final answer: A