Question

The most pure form of Iron is :

• A. Cast Iron
• B. Pig Iron
• C. Wrought Iron
• D. Steel

Hint:

Purity of iron forms is mainly related to carbon content: % Option (m) {Pig Iron:} Highest carbon (least pure). % Option (n) {Cast Iron:} High carbon. % Option (o) {Steel:} Medium carbon (alloy, properties vary). % Option (p) {Wrought Iron:} Lowest carbon (most pure commercial iron). Think: Wrought iron is "worked" iron, refined to remove impurities.

Answer 1

The Correct Option is C

Concept: Iron is commercially produced in several forms, which differ mainly in their carbon content and the presence of other impurities. Purity refers to the percentage of iron, with lower carbon and impurity content indicating higher purity. Step 1: Understanding different forms of commercial Iron (e) Pig Iron: This is the crude iron obtained directly from a blast furnace. It has a high carbon content, typically 3.5% to 4.5%, and also contains other impurities like silicon, manganese, phosphorus, and sulfur. It is very brittle and not very useful directly for most applications. (f) Cast Iron: Produced by re-melting pig iron, often with scrap iron and steel, and then casting it into molds. The carbon content is typically 2% to 4%. It is hard and brittle but has good fluidity for casting. Impurities are still present. (g) Wrought Iron: This is historically the purest form of commercial iron. It has a very low carbon content, usually less than 0.08% (often around 0.02-0.03%), and very few other impurities. It is tough, malleable, and ductile, but softer than steel. It contains some slag (fibrous inclusions of iron silicate), which gives it a characteristic grain. (h) Steel: Steel is an alloy of iron and carbon, typically with a carbon content between 0.2% and 2.1% by weight. The properties of steel can be varied widely by changing the carbon content and adding other alloying elements (like manganese, chromium, vanadium, tungsten). Steel is generally stronger and more versatile than cast iron or wrought iron. Step 2: Comparing Carbon Content (as an indicator of purity) (i) Pig Iron: \(\sim 3.5 - 4.5%\) C (Least pure) (j) Cast Iron: \(\sim 2 - 4%\) C (k) Steel: \(\sim 0.2 - 2.1%\) C (l) Wrought Iron: \(< 0.08%\) C (Most pure commercial form) Step 3: Identifying the most pure form Based on the low carbon content and fewer impurities, Wrought Iron is considered the most pure form of commercial iron among the options.