What is not true about borax ?

Options

A. It is a useful primary standard for titrating against acids
B. one mole of borax contains 4B-O-B bonds
C. Aqueous solution of borax can be used as buffer
D. it is made up of two triangular `BO_(3)` units and two tetrahedral `BO_(4)` units

Answer

B

Explanation

In borax `(Na_(2)B_(4)O_(7).10H_(2)O)`, among 10 water molecules 2 molecules are part of structure, i.e., exists `Na_(2)[B_(4)O_(5)(OH)_(4)]*8H_(2)O`

`Na_(2)[B_(4)O_(5)OH)_(4)*8H_(2)O+2HCl to 2NaCl+4H_(3)BO_(3)+5H_(2)O`
Methyl orange (pH=3.7) is used to detect end point. Aq. solution of borax acts as buffer, as borax is salt of strong base NaOH annd weak acid `H_(3)BO_(3)`.