What is the result of an insufficiently applied oxide film on aluminum?

An insufficiently applied oxide film on aluminum leads to accelerated corrosion. This is because aluminum naturally forms a protective oxide layer when exposed to oxygen; however, if this layer is thin or improperly formed, it cannot effectively protect the underlying metal from environmental factors, such as moisture and salts. As a result, the aluminum is more susceptible to corrosion, leading to deterioration of its structural integrity and performance.

The production of the oxide film occurs spontaneously when aluminum is exposed to oxygen, and its effectiveness is crucial in creating a barrier to moisture and other corrosive agents. Inadequate oxide formation results in exposure of the raw aluminum, hence allowing electrochemical reactions that contribute to corrosion.

The other choices do not accurately reflect the impact of a weak oxide film. The aluminum does not remain unreactive—rather, it becomes more reactive to environmental conditions. It also does not become more conductive; in fact, an effective oxide layer enhances the material's properties by providing insulation against conductivity. Lastly, an insufficient oxide film does have an impact on the aluminum surface by making it more prone to corrosion rather than having no effect at all.