Question

Borax structure contains?
A. Two $B{O}_4$ groups and two $B{O}_3$ groups
B. Four$B{O}_4$ groups only
C. Four $B{O}_3$ groups only
D. Three $B{O}_4$ groups and one $B{O}_3$ group

Answer 1

Hint: Borax is a compound of boron it has a structure having tetra nuclear units. Borax is a salt that contains water of crystallization. It is an important compound of boron. It gives a famous borax bead test on subjection with heat to form transparent beads like glass. They consist of sodium Meta borate and boric anhydride.

Complete answer:
Borax is an important compound of boron. It has a formula $N{a}_2[B_4{O}_5{(OH)}_4].8H_{2}O$ and thus also called as sodium tetraborate. Its structure consist of tetra nuclear units of the formula${\left[B_4{O}_5{(OH)}_4\right]}^{2-}$
The structure of borax consists of an arrangement with 4 boron atoms such that 2 boron atoms form 3 – coordinate bonds, while the other 2 boron atoms form 4 – coordinate bonds. Thus the structure gives rise to the formation of two groups of boron and oxygen arrangement. The arrangement where 2 boron atoms are in the form of tetrahedral atoms having two $B{O}_4$groups, and the other arrangement where the other 2 boron atoms have a planar arrangement with 3 oxygen atoms as $B{O}_3$ groups. The structure of borax is as follows:

Hence, the borax structure contains two $B{O}_4$ groups and two $B{O}_3$groups.

So, option A is correct.

Note:
Borax is one of the most useful compounds of boron. It is used in preparing antiseptic medicinal soaps, for water softening, manufacturing borosilicate glass, soldering etc. It gives a known borax bead test that when subjected to heating it forms glass like beads that are important and useful in qualitative analysis of radicals.