Question

The conversion of pig iron to steel frequently requires the addition of:
1.oxygen or iron oxide
2.transition elements
3.inner transition elements
4.silica
A)I, II, III
B)I, II
C)II, II
D)I only.

Answer 1

Industrial steel is a widely used material and comes in a variety of constituent configurations. Steels of any type usually have a very high percentage of iron. Any form of the steel contains anywhere between 0.05 to $0.3\%$ of carbon. While the majority constituent of steel, i.e. Iron, most contributes more or less $99\%$ to the percentage composition of the steel.

Complete step by step answer:
We must know that different types of steel are used for different applications all over the industry. There are instances where a softer and more ductile steel is required in comparison to hard and stiff steel. This hardness in the different types of steels is determined by carbon composition.
Both mild steel and hard steel have more or less $99\%$ of Iron with the variation being in the form of carbon and other minor constituents.
In the case of Pig Iron, we must know that Pig iron is produced by smelting Iron ore with a high carbon fuel. Chemically speaking, Pig iron is obtained by reducing Iron ore with coke or anthracite in a blast furnace. This significantly increases the percentage composition of Carbon. This indirectly means that the percentage of iron is reduced. Experimentally it is found that iron contributes only about $91 - 94\%$ to the total composition of Pig iron.
In the conversion of pig iron to steel frequently requires the addition of oxygen or iron is important. Oxygen and iron oxidize the impurities of iron like silica, manganese, which are getting removes in the forms of slag. And the addition of transition metal is also important which reacts with unreduced FeO and reduces them. Also adding transition metals steel becomes harder and increases the tensile strength.
So, the correct option is B.

Note: In the case of wrought iron, you should know that Wrought iron is produced in a process wherein the iron sample is removed from the furnace and worked on directly. This helps in removing molten slag. Hence the percentage of Iron present in Wrought Iron is also very high in the range upwards of $98\%$