Question

Match the column I with column II and mark the appropriate choice. $$ \begin{array}{|l|l|l|l|} \hline {\text { Column I is }} & & {\text { Column II }} \\ \hline \text { (A) } & \text { Galena } & \text { (i) } & \text { Abrasive } \\\ \hline \text { (B) } & \text { Diamond } & \text { (ii) } & \text { Metal carbonyls } \\ \hline \text { (C) } & \text { Carbon monoxide } & \text { (iii) } & \text { Hydrides of Si } \\ \hline \text { (D) } & \text { Silanes } & \text { (iv) } & \text { An ore of lead } \\ \hline \end{array} $$ (a) \((\mathrm{A}) \rightarrow(\mathrm{iv}),(\mathrm{B}) \rightarrow(\mathrm{ii}),(\mathrm{C}) \rightarrow(\mathrm{i}),(\mathrm{D}) \rightarrow\) (iii) (b) \((\mathrm{A}) \rightarrow(\mathrm{iv}),(\mathrm{B}) \rightarrow(\mathrm{i}),(\mathrm{C}) \rightarrow(\mathrm{ii}),(\mathrm{D}) \rightarrow(\mathrm{iii})\) (c) \((\mathrm{A}) \rightarrow(\mathrm{ii}),(\mathrm{B}) \rightarrow(\mathrm{i}),(\mathrm{C}) \rightarrow(\mathrm{iii}),(\mathrm{D}) \rightarrow\) (iv) (d) (A) \(\rightarrow(\mathrm{i}),(\mathrm{B}) \rightarrow(\mathrm{ii}),(\mathrm{C}) \rightarrow(\mathrm{iii}),(\mathrm{D}) \rightarrow(\mathrm{iv})\)

Short answer

(a) \text{(A) -> (iv), (B) -> (i), (C) -> (ii), (D) -> (iii)}

Step-by-step solution

Match Item (A) - Galena

Identify what Galena is associated with among the options in Column II. Galena is known to be an ore of lead, which matches with item (iv). So, (A) should be matched with (iv).

Match Item (B) - Diamond

Identify what Diamond is associated with among the options in Column II. Diamond is known for its hardness and is often used as an abrasive, which matches with item (i). So, (B) should be matched with (i).

Match Item (C) - Carbon Monoxide

Identify what Carbon Monoxide is associated with among the options in Column II. Carbon monoxide can form metal carbonyls with transition metals, which matches with item (ii). So, (C) should be matched with (ii).

Match Item (D) - Silanes

Identify what Silanes are associated with among the options in Column II. Silanes are hydrides of silicon, which matches with item (iii). So, (D) should be matched with (iii).

Combine Matches to Find the Correct Option

Combine the identified matches from Steps 1 to 4 to find the complete correct matching sequence. You can use process of elimination with the multiple-choice answers provided. The matches are (A) -> (iv), (B) -> (i), (C) -> (ii), and (D) -> (iii).

Key concepts

Galena and Lead Ore

Galena, with its shiny, gray cubic crystals, is more than just a pretty mineral; it's the primary ore of lead and has been used for thousands of years. The name 'Galena' comes from the Latin word for lead sulfide, and indeed, galena's chemical formula is PbS, marking its high lead content.

Found in hydrothermal veins in limestone or in volcanic rock, galena also often contains silver, making it an important source of this precious metal as well. Lead, extracted from galena, is used in batteries, bullets, and radiation shielding, reflecting its density and relatively low melting point. Students should remember galena not only for its luster but also for its central role in the production of metallic lead.

Diamond and Abrasives

A diamond's allure stretches beyond its sparkle—it is also the hardest natural material known to humanity. Its unparalleled hardness means that diamonds can scratch virtually any surface, leading to their widespread use in industrial applications as abrasives.

In fact, a diamond's toughness makes it invaluable in cutting, drilling, and grinding other hard materials. This characteristic is a consequence of its crystal structure: each carbon atom in a diamond is tetrahedrally coordinated to four other carbon atoms, creating an extremely rigid lattice. Despite its high cost, the diamond's durability and efficiency in shaping building materials, as well as in abrasive powders and grinding wheels, compensate for the investment.

Carbon Monoxide and Metal Carbonyls

Carbon monoxide's notorious reputation as a poisonous gas overshadows its intriguing role in forming metal carbonyls. These complex compounds consist of carbon monoxide bound to transition metals and are fascinating due to their wide range of industrial and laboratory applications.

What makes carbon monoxide a good ligand for metal centers is its ability to donate electron density from its carbon to the metal and accept electron density through its oxygen end, a characteristic that chemists refer to as 'synergistic bonding'. Metal carbonyls are important in various catalytic processes, including the manufacture of hydrocarbons in the Fischer-Tropsch process, and in fine chemical synthesis.

Silanes and Silicon Hydrides

When silicon bonds with hydrogen, the result is silanes, a group of compounds known as silicon hydrides. Silanes, which have the general formula (SiH_n where n is 2, 4, or 6, serve as the silicon analog of alkanes (hydrocarbons).

These compounds are less stable than their carbon counterparts, making them reactive and useful as reducing agents or as chemical building blocks in the production of silicon-based materials. Their ability to form silicon-oxygen-silicon linkages, for instance, is a key step in creating silicone polymers, widely used in sealants, adhesives, and coatings. Understanding silanes helps students grasp the basics of silicon chemistry and its significance in materials science.