Chromium is added to stainless steel as it provides
**Core Concept**
Chromium is added to stainless steel to provide corrosion resistance and improve its mechanical properties. The addition of chromium forms a thin layer of chromium oxide on the surface, protecting the underlying metal from corrosive substances.
**Why the Correct Answer is Right**
Chromium reacts with oxygen to form a stable chromium oxide layer, which prevents further corrosion by blocking the access of corrosive substances to the underlying metal. This property is known as passivation. The chromium oxide layer also increases the strength and hardness of the steel.
**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect, as chromium is not added to stainless steel for its magnetic properties. While chromium can be ferromagnetic, its primary function in stainless steel is to provide corrosion resistance.
**Option B:** Incorrect, as chromium is not added to stainless steel for its thermal conductivity. Although chromium has a moderate thermal conductivity, its primary function in stainless steel is to provide corrosion resistance.
**Option C:** Incorrect, as chromium is not added to stainless steel for its electrical conductivity. While chromium has a moderate electrical conductivity, its primary function in stainless steel is to provide corrosion resistance.
**Clinical Pearl / High-Yield Fact**
Chromium is also an essential micronutrient for humans, playing a crucial role in carbohydrate and fat metabolism. Its deficiency can lead to impaired glucose tolerance and insulin resistance.
**Correct Answer:** C.