Question

Borax, disodium tetraborate is an important boron compound, a mineral, and a salt of boric acid. The number of terminal B- - - - - OH presents in borax is?
(A) 3
(B) 4
(C) 5
(D) 6

Answer 1

Hint: Borax is also known as sodium borate, sodium tetraborate or disodium tetraborate. It is a colorless crystalline solid that dissolves in water. It has 2 four-coordinate boron centres and 2 three-coordinate boron centres.

Complete step by step solution:
In nature, borax combines to form boric acid and inorganic salts called borates. Borax is a form of hydrous sodium borate which occurs naturally in a region where evaporation of saline lake takes place.
Anhydrous sodium tetraborate or disodium tetraborate is represented by $N{a}_2{B}_4{O}_7$ . From a chemical perspective borax has 2 four-coordinate boron centres and 2 three-coordinate boron centres.

Disodium tetraborate has 4 B-OH bonds, as we can see in the structure.
Therefore, the correct answer is option B.

Note:
Borax is an important compound of boron because it has many important uses which are as follows, Borax is a component of many daily life products like detergents, cosmetics, and enamel glazes. Borax is used to make buffer solution, it is used as fire retardant, it is also used as an antifungal compound. Borax is used in the manufacture of fiberglass and as a flux in metallurgy. Borax is used as a neutron-capture shield for radioactive sources. It gives a good texture agent, therefore used in cooking. It is used in developing photographs. It is used as an alkali while developing photographs. It is also used as an insecticide. In artisanal gold mining, borax is used as a part of the process of eliminating the toxic mercury in the gold extraction process. Borax is used and added in flame to give it a yellow green color.
Borax is used for many cleaning purposes and can be used to make homemade laundry detergent. It even keeps ants and other pests away. It is also used as a flux in soldering and welding.
Borax even has a different number of molecules of water of crystallization such as sodium tetraborate pentahydrate and sodium tetraborate decahydrate.