Question

Stainless steel does not rust because:
A) Chromium and nickel combine with iron.
B) Chromium forms an oxide layer and protects iron from rusting.
C) Nickel present in it, does not rust.
D) Iron forms a hard chemical compound with chromium present in it.

Answer 1

Hint: We know that an alloy is a homogeneous mixture of two or more metals or a metal and small amount of non-metals. It is also known that alloy is prepared by mixing the various metals in molten state in required proportions and then cooling their mixture to the room temperature.

Complete answer:
When we alloyed iron metal with other metals such as chromium and nickel, we get an alloy called stainless steel which is strong, tough and does not rust at all. Since stainless steel resists corrosion, it is used for making cooking utensils, knives, scissors, tools and ornamental pieces. The use of stainless steel in such application is because of the interactive forces present in between its constituent and the surrounding atmosphere. The constituents of stainless steel are iron, chromium, manganese, silicon, and carbon along with the significant amount of nickel and molybdenum.
The presence of chromium is necessary which reacts with oxygen present in air and forms the protective layer due to which the corrosion gets prevented. Also, the corrosion due to the action of excess oxygen and water present in the air which is accessible to the surface of metal gets prevented by this layer of oxide.

Hence, we can conclude that the correct option is B.

Note: We know that the strength and other properties of steel vary with the percentage of carbon present in it. Also it is very hard, tough and strong, steel is used for making nails, screws, grinders, bridges and railway lines. It is also used for the construction of buildings, vehicles and ships.