Question

The number of \[-OH\] units directly bonded to borax atoms in borax is:
A. 10
B. 4
C. 5
D. 3

Answer 1

Hint: Sodium borate, sodium tetraborate, and disodium tetraborate are further names for borax. It is a crystalline substance without colour that dissolves in water. It has two boron centres with four coordinates and two with three coordinates.

Complete Step by Step Solution:
Borax is a significant boron compound because it has numerous beneficial applications, including those listed below. Borax is an ingredient in a variety of everyday items, including detergents, cosmetics, and enamel glazes. In addition to being used as a fire retardant and an antifungal agent, borax is also used to manufacture buffer solutions. Borax is used as a flux in metallurgy and in the production of fibreglass. Borax is used to insulate radioactive sources from neutrons. It provides an excellent textural agent and is utilised in cooking. In processing photos, it is employed. In the process of developing pictures, it serves as an alkali. Insecticide is another application for it.
Borax is used in artisanal gold mining as a step in the process of removing the hazardous mercury from the gold extraction process. A flame-added mixture of borax is used to give it a yellow-green hue.
Borax may be used to manufacture homemade laundry detergent and is utilised for a variety of cleaning tasks. Even ants and other bugs stay away from it. It is additionally employed in soldering and welding as a flux.
Borax even crystallises as sodium tetraborate pentahydrate and sodium tetraborate decahydrate, which have differing numbers of water molecules.
The structure of Borax\[(N{{a}_{2}}{{B}_{4}}{{O}_{7}}.10{{H}_{2}}O)\]is given as:

From the structure we can see that there are 4\[B-OH\]bonds.
Hence, the correct option is B. 4 that is there are four \[-OH\]directly attached to borax.

Note: Borax naturally reacts with other substances to produce borates, an inorganic salt family. A region where saline lake evaporation occurs naturally produces borax, which is a form of hydrous sodium borate. The chemical symbol for sodium tetraborate, sometimes known as disodium tetraborate, is\[N{{a}_{2}}{{B}_{4}}{{O}_{7}}\]. Borax has two boron centres with four coordinates and two with three coordinates from a chemical standpoint.