Question

Borax glass is a mixture of :
A.\[{{NaB}}{{{O}}_2} + {{{B}}_2}{{{O}}_3}\]
B.\[{{N}}{{{a}}_2}{{{B}}_4}{{{O}}_7} + {{{B}}_2}{{{O}}_3}\]
C.\[{{{H}}_2}{{{B}}_4}{{{O}}_7} + {{{B}}_2}{{{O}}_3}\]
D.\[{{N}}{{{a}}_2}{{{B}}_4}{{{O}}_7}.{{10}}{{{H}}_2}{{O}} + {{{B}}_2}{{{O}}_3}\]

Answer 1

Hint: Borax is a compound which has parent Atom boron. When you heat Borax with some of the compounds, it gives glassy beads. When you. This glassy bead is of at most importance in the quality analysis of coloured compounds.

Complete step by step answer:
Borax is prepared from tincal, It is obtained from the lakes, which are dried up. To remove all the impurities, such as dust and sand from it, it is being boiled and then filtered. And therefore the crystals of Borax are separated from it.
Borax appears as a crystalline white solid. It’s solubility in water depends on the temperature of the water. In cold water it is less soluble, on the other hand, in hot water it is more soluble
When dissolved in water, it forms an alkaline solution due to hydrolysis. It has antiseptic properties which help it to produce and be used in medicinal soaps. It is also used to produce enamels and glazes for earthenwares.
The Borax powder is taken on a platinum wire loop and is heated, this Borax powder loses the water in it and forms a puffy mass. On heating it further, it melts and forms a glassy bead which is formed of sodium metaborate \[\left( {NaB{O_2}} \right)\] and boric anhydride \[\left( {{B_{_2}}{O_3}} \right)\]. This bead then is covered with the solution of hydrochloric acid and the compound which is to be analysed and heated again which forms a colourful bead. The colour of the bead can be used to identify the cation present.
And hence option A is the correct answer.

Note:
Always remember that the borax bead test is only used when the compound is coloured. If the compound does not contain any colour or it is colourless, then the borax bead test is not considered on that compound, and we will directly move on to the further step.