Animated Solution for Chemistry - Metallurgy: Match List-I with List-II. $\begin{array}{ll}\text{List-I}& \text{List-II}\\ \text{(Ore)}& \text{(Element present)}\\ \text{A. Kernite}& \text{(i) Tin}\\ \text{B. Cassiterite}& \text{(ii) Boron}\\ \text{C. Calamine}& \text{(iii) Fluorine}\\ \text{D. Cryolite}& \text{(iv) Zinc}\end{array}$ Choose the most appropriate answer from the options given below.

A Matching Masterclass

Metallurgy is not just about extracting metals; it is about understanding the very earth we walk on. The ores we mine are complex chemical compounds, and knowing their exact compositions is the first crucial step in any extraction process. In this problem, we are tasked with matching four distinct ores to their primary constituent elements. Let's break down each ore, explore its chemical identity, and uncover the logic behind the correct matches.

The Boron Connection

Our first candidate is Kernite. If you have studied the p-block elements, you might recall that boron is primarily found in the form of borates. Kernite is a naturally occurring hydrated sodium borate.

Its chemical formula is $\mathrm{N}{\mathrm{a}}_2{\mathrm{B}}_4{\mathrm{O}}_7\cdot 4{\mathrm{H}}_2\mathrm{O}$, which makes it sodium tetraborate tetrahydrate. It is closely related to the more famous borax ($\mathrm{N}{\mathrm{a}}_2{\mathrm{B}}_4{\mathrm{O}}_7\cdot 10{\mathrm{H}}_2\mathrm{O}$), differing only in the number of water molecules of crystallization. Because its formula is rich in boron, it is unequivocally an ore of Boron. Therefore, A matches perfectly with (ii).

The Ancient Tin Oxide

Next, we encounter Cassiterite. This ore has been historically significant since the Bronze Age, as it is the primary source of tin.

Chemically, cassiterite is an oxide ore with the formula $\mathrm{Sn}{\mathrm{O}}_2$ (tin dioxide). It is a heavy, generally dark-colored mineral that is highly resistant to weathering, which is why it is often found in alluvial deposits. Since its sole metallic component is tin, B naturally pairs with (i).

The Zinc Carbonate

Moving on to Calamine. This name can sometimes be a trap for students. While 'calamine lotion' used in medicine is a mixture of zinc oxide and a small amount of iron(III) oxide, in the context of mineralogy and metallurgy, calamine refers to a carbonate ore of zinc.

Its chemical formula is $\mathrm{ZnC}{\mathrm{O}}_3$, and it is also known by the mineralogical name smithsonite. It is a vital source for the extraction of zinc. Thus, the primary element here is Zinc, meaning C matches with (iv).

The Fluorine Source

Finally, we have Cryolite. This is a legendary mineral in the world of industrial chemistry. It plays an indispensable role in the Hall-Heroult process for the electrolytic extraction of aluminium from alumina.

Its chemical formula is $\mathrm{N}{\mathrm{a}}_3\mathrm{Al}{\mathrm{F}}_6$, known systematically as sodium hexafluoroaluminate. While it does contain aluminium and sodium, looking at our available options in List-II, the unique element present here is Fluorine. Cryolite acts as a solvent that lowers the melting point of alumina and increases the electrical conductivity of the melt. Therefore, D matches with (iii).

By systematically analyzing the chemical formula of each ore, we have successfully decoded the matrix:

A. Kernite $\to$ (ii) Boron B. Cassiterite $\to$ (i) Tin C. Calamine $\to$ (iv) Zinc D. Cryolite $\to$ (iii) Fluorine

When we look at the given options, the sequence A-(ii), B-(i), C-(iv), D-(iii) corresponds exactly to option (b). This problem beautifully illustrates how a solid grasp of chemical formulas is the ultimate key to mastering the principles of metallurgy.