The correct option is (c) 2 and 3 only.
Explanation
Steel is primarily an alloy of iron and carbon. To enhance specific physical and chemical properties-such as hardness, tensile strength, ductility, and resistance to corrosion-various other elements are introduced to create "alloy steels."Statement-wise Analysis:
- Statement 1 is Incorrect: Mercury is not used as an alloying element in steel production. Chemically, iron is one of the few metals that does not form an amalgam (alloy) with mercury. Consequently, iron flasks are used to store and transport mercury.
- Statement 2 is Correct: Nickel is a widely used alloying element. It improves the toughness, strength, and ductility of steel. Crucially, it enhances corrosion resistance and is a key component in the production of stainless steel (often alongside chromium).
- Statement 3 is Correct: Copper is added to steel, particularly in "weathering steels" (such as Corten steel), to improve resistance to atmospheric corrosion. It promotes the formation of a stable, protective oxide layer on the surface that prevents further rusting.
Key Takeaway: Iron does not form amalgams with mercury. Common alloying agents for steel include Manganese (hardness), Nickel (toughness and corrosion resistance), Chromium (stainless properties), and Copper (corrosion resistance).