Question

Match the column I with column II and mark the appropriate choice. \(\begin{array}{|l|l|l|l|} \hline \text { (A) } & \text { Borax } & \text { (i) } & \mathrm{Na}_{3} \mathrm{AlF}_{6} \\ \hline \text { (B) } & \text { Inorganic benzene } & \text { (ii) } & \mathrm{N}_{2} \mathrm{~B}_{\mathbf{1}} \mathrm{O}_{7} \mathbf{~} \mathbf{1 0} \mathrm{H}_{2} \mathrm{O} \\ \hline \text { (C) } & \text { Cryolite } & \text { (iii) } & \mathbf{A}_{2} \mathrm{O}_{3} \cdot \mathbf{2 H}_{2} \mathrm{O} \\ \hline \text { (D) } & \text { Bauxite } & \text { (iv) } & \mathrm{B}_{3} \mathrm{~N}_{3} \mathrm{H}_{6} \\ \hline \end{array}\) (a) \((\mathrm{A}) \rightarrow(\mathrm{ii}),(\mathrm{B}) \rightarrow(\mathrm{iv}),(\mathrm{C}) \rightarrow(\mathrm{i}),(\mathrm{D}) \rightarrow\) (iii) (b) \((\mathbf{A}) \rightarrow(\mathrm{i}),(\mathrm{B}) \rightarrow(\mathrm{ii}),(\mathrm{C}) \rightarrow(\mathrm{iii})\), (D) \(\rightarrow\) (iv) (c) \((A) \rightarrow(i i),(B) \rightarrow(\) iii), \((C) \rightarrow(i),(D) \rightarrow\) (iv) (d) \((A) \rightarrow(\) iii), \((B) \rightarrow(i),(C) \rightarrow(i i)\), (D) \(\rightarrow\) (iv)

Short answer

(A) -> (ii), (B) -> (iv), (C) -> (i), (D) -> (iii)

Step-by-step solution

Identify the Correct Chemical Formulas

Match each compound with the corresponding chemical formula. (A) Borax is a compound that is usually represented as Na2B4O7·10H2O. (B) Inorganic benzene is B3N3H6, which is structurally similar to benzene but consists of alternating boron and nitrogen atoms. (C) Cryolite is known chemically as Na3AlF6. (D) Bauxite is an ore of aluminum and can be represented as A2O3·2H2O where 'A' stands for aluminum, so the formula becomes Al2O3·2H2O.

Match Compounds to their Formulas

Using the information from Step 1, match each compound to its chemical formula. (A) Borax matches with (ii) Na2B4O7·10H2O. (B) Inorganic benzene matches with (iv) B3N3H6. (C) Cryolite matches with (i) Na3AlF6. (D) Bauxite matches with (iii) Al2O3·2H2O.

Key concepts

Borax Formula

Borax, commonly known as sodium borate, is a mineral and a salt of boric acid. The formula of borax is often referred to as Na₂B₄O₇·10H₂O. This means that borax is composed of two sodium ions, four boron atoms, and seven oxygen atoms, along with ten molecules of water of crystallization, making it a hydrated salt.

In the laboratory, borax is utilized for various purposes, including as a flux in metal welding, in the creation of putty, and as a cleaning agent. Its unique properties also make it useful in the manufacture of glazes and enamels in ceramics industry.

Inorganic Benzene Structure

Inorganic benzene, which is borazine, has a fascinating structure with the formula B₃N₃H₆. Structurally analogous to carbon benzene, inorganic benzene consists of alternating boron (B) and nitrogen (N) atoms in a hexagonal ring, with each boron and nitrogen atom also bonded to a hydrogen atom. Due to this arrangement, borazine is sometimes also referred to as 'inorganic benzene'.

However, even though the structures are similar, the properties of borazine vastly differ from those of organic benzene. This is mainly due to the differing electronic structures of boron and nitrogen compared to carbon.

Cryolite Composition

Cryolite is an essential mineral primarily used in the production of aluminum. The composition of cryolite can be expressed as Na₃AlF₆. This indicates that each molecule of cryolite contains three sodium atoms, one aluminum atom, and six fluorine atoms.

This mineral is especially important in the Hall-Héroult process, where it serves to lower the melting point of aluminum oxide, thereby reducing the energy required for the extraction of aluminum. The unique properties of cryolite, including its ability to dissolve oxides and its high stability at elevated temperatures, make it ideal for this and other industrial processes.

Bauxite Chemical Formula

Bauxite is the primary ore of aluminum and has a typical chemical formula of Al₂O₃·xH₂O, where 'x' can be various numbers of water molecules. This hydrate form indicates that bauxite is composed of aluminum oxide mixed with water. The most common bauxite form is known as monohydrate, which has a formula of Al₂O₃·2H₂O.

Bauxite is a vital raw material in the alumina refineries where it is processed to extract aluminum oxide, which is then used to produce aluminum metal. Its composition can also include mixtures of iron oxides, silicon oxide (silica), and other impurities that affect the processing and quality of the extracted aluminum.