Question

Borax is converted into crystalline boron by the following steps:
$Borax\xrightarrow{X}{{H}_{3}}B{{O}_{3}}\xrightarrow{\Delta }{{B}_{2}}{{O}_{3}}\xrightarrow[\Delta ]{Y}B$
A.HCl, Mg
B.HCl, C
C.C, Al
D.HCl, Al

Answer 1

Boron is a chemical element with atomic number 5 and the symbol B. It is a brittle, dark, glossy metalloid in its crystalline form, and a brown powder in its amorphous form. Because it is the lightest member of the boron group, it possesses three valence electrons for making covalent bonds, resulting in a variety of compounds including boric acid, borax, and the ultra-hard crystal boron carbide.

Complete answer:
Borax is a boron compound, a mineral, and a salt of boric acid. It is also known as sodium borate, sodium tetraborate, or disodium tetraborate. Borax powder is a white powder made up of soft colorless crystals that dissolve in water. Borax is a term that refers to a group of minerals or chemical compounds that differ in their crystal water concentration, and it is most commonly used to refer to the octahydrate. Borax that is marketed commercially is partly dehydrated.
Borax may also be turned to boric acid and other borates, which have a variety of uses. The "decahydrate" is stable enough to serve as a main standard in acid-base titrimetry. Borax generates a yellow green hue when put to a flame. Due to the overpowering yellow hue of sodium, borax is not utilized for this purpose in fireworks. Boric acid is used to turn methanol flames into a translucent green hue.
In the first stage, a heated concentrated solution of borax is treated with hydrochloric acid or sulphuric acid to produce boric acid. After concentration and chilling, the resultant solution yields boric acid crystals. HCl or ${{H}_{2}}S{{O}_{4}}$ is the acid employed here.
$N{{a}_{2}}[{{B}_{4}}{{O}_{5}}{{(OH)}_{4}}].8{{H}_{2}}O\xrightarrow{Acid(HCl)}{{H}_{3}}B{{O}_{3}}\xrightarrow[Mg]{\Delta }2B+MgO$
Hence X = HCl and Y =Mg

Hence option a is correct.

Note:
When welding iron and steel, a flux made of borax and ammonium chloride is utilized. The undesirable iron oxide (scale) melts at a lower temperature, allowing it to flow off. When soldering jewelry metals like gold or silver, borax combined with water is used as a flux, allowing the molten solder to wet the metal and flow evenly into the connection. [requires citation] Borax is also an excellent flux for "pre-tinning" tungsten with zinc, which makes it soft-solderable. Forge welding frequently uses borax as a flux.