Match Column I with Column II

A-s; B-r; C-p; D-q

The correct answer is option 1. A-s; B-r; C-p; D-q.

Let us look into each of the matches in detail:

A. Gallium - Zone refining (s):

Zone refining is a purification technique commonly used for refining materials with high melting points and high thermal conductivity, such as gallium. Here's how the process generally works:

Setup: A rod of impure gallium is placed horizontally in a furnace. The impurities are distributed unevenly along the length of the rod.

Heating: One end of the rod is heated to its melting point, while the rest of the rod remains solid. This creates a molten zone at one end of the rod.

Movement: The molten zone is slowly moved along the length of the rod. As it moves, impurities tend to concentrate either ahead of or behind the zone, depending on their solubility in the liquid gallium versus the solid gallium.

Zone Refinement: When the impurities concentrate at one end of the rod, that portion is cut off, leaving behind a more purified section. The process is repeated multiple times, each time creating a more purified section of gallium.

Final Purification: After several passes, the impurity concentration in the gallium is significantly reduced, resulting in a highly purified form of gallium.

Zone refining is a slow process but can achieve very high levels of purity, often exceeding 99.9999%. It's widely used in semiconductor manufacturing, where purity is crucial for producing high-quality electronic devices.

B. Tin - Liquation (r):
Tin is a metal that has been used by humans for thousands of years. It is commonly used in various alloys, solder, and as a protective coating for other metals. Liquation is a process used for the purification of metals that have different melting points. Tin undergoes liquation when impure tin is heated to a temperature slightly above its melting point. Since impurities often have higher melting points than tin, they remain solid while the tin melts. The molten tin is then collected separately, leaving behind the solid impurities. This process helps to separate tin from its impurities, resulting in a more purified form of the metal.

C. Zirconium - van Arkel (p):

The van Arkel method, also known as the iodide process, is a purification technique used for refining reactive metals like zirconium. Here's an overview of how the van Arkel method works for purifying zirconium:

Formation of Zirconium Tetraiodide \((ZrI_4)\):

Zirconium metal is reacted with iodine gas at high temperatures to form zirconium tetraiodide \((ZrI_4)\). The reaction typically occurs in a closed vessel or reactor chamber under controlled conditions to prevent contamination and ensure efficient conversion.

Sublimation:

Zirconium tetraiodide is a volatile compound that readily sublimes at relatively low temperatures. The mixture of zirconium tetraiodide and excess iodine is heated, causing the \(ZrI_4\) to sublime, leaving behind any unreacted impurities or non-volatile contaminants.

Collection:

The sublimed zirconium tetraiodide is collected on a cooler surface within the reaction chamber or in a separate collection chamber. The collection surface is often kept at a lower temperature to facilitate the condensation and solidification of the purified zirconium tetraiodide.

Reduction:

Zirconium tetraiodide is then reduced back to zirconium metal through a process called "thermochemical disproportionation." Typically, the reduction is carried out by heating the \(ZrI_4\) in the presence of a reducing agent, such as metallic calcium or magnesium, at high temperatures. During the reduction process, the zirconium tetraiodide decomposes, yielding pure zirconium metal and iodine gas as byproducts.

Separation and Recovery:

The resulting zirconium metal is separated from any residual impurities or byproducts. Any remaining iodine gas can be captured and recycled for future use in the process, minimizing waste and ensuring efficiency.

The van Arkel method is known for its ability to produce high-purity zirconium suitable for various applications, including nuclear reactors, aerospace components, and chemical processing equipment. However, the process requires careful control of reaction conditions and may involve multiple purification steps to achieve the desired level of purity.

D. Nickel - Mond's Process (q):

Nickel is a silvery-white lustrous metal with a slight golden tinge. It is a hard, ductile transition metal that is highly resistant to corrosion and tarnish. Mond's process is a method for refining nickel. In this process, nickel is reacted with carbon monoxide at around 50-60°C to form nickel carbonyl, a volatile compound. This compound is then decomposed at higher temperatures (around 200-250°C) to yield pure nickel metal. This process is particularly useful for refining nickel from ores that contain other metals as impurities.

In summary, each of these processes is used for the purification of specific metals, and they are matched correctly with the respective metals in option 1 (A-s; B-r; C-p; D-q).