Answer
See the definitions and explanations of involvement below:
Work Step by Step
(a) Slag is a byproduct of steel-making and contains the impurity SiO2.
(b) Pig iron is the impure product of iron metallurgy (containing 3–4% C and other impurities). This is later purified by the basic oxygen process. It is usually in the form of oblong blocks.
(c) Steel refers to iron alloyed with other elements to attain desirable properties. An example is a stainless steel, which contains iron as well as chromium.
(d) The basic oxygen process is used to purify the pig iron and obtain carbon steel.
