What is the primary feature of non-ferrous metals?

The primary feature of non-ferrous metals is that they do not contain iron. This characteristic distinguishes them from ferrous metals, which contain iron and are prone to rusting and corrosion when exposed to moisture and air. Non-ferrous metals, such as aluminum, copper, and zinc, are valued for their resistance to corrosion, lighter weight, and higher conductivity compared to ferrous metals. This absence of iron not only affects their physical properties but also expands their applications in various industries, making them suitable for situations where corrosion resistance or lightweight materials are desired.

In this context, the other choices can be seen in relation to the defining features of non-ferrous metals. Non-ferrous metals are not inherently magnetic, which directly relates to their lack of iron content, as iron's presence generally contributes to magnetic properties. While some non-ferrous metals do show corrosion resistance, it’s not accurate to say they all do not corrode easily since specific behavior can vary between different types of non-ferrous metals and their alloys.