Which of the following staments are incorrect in context of borax?

Options

A. It is made up to two triangular `BO _(3)` units and two tetrahedral `BO _(4)` units
B. One mole of borax can be used as buffer
C. It is a useful primary standard for titrating against acids
D. Aqueous solution of borax can be used as buffer

Answer

B

Explanation

Borax is `Na _(2) B _(4) O _(7). 10 H _(2) O` in which 1 molecules of water among 10 molecules forms a part of structure and exists as `Na_(2) [ B _(4) O _(5) ( OH) _(4) ]8H_(2)O`

`N a _(2) [ B _(4) O _(5) (OH) _(4) ]. 8 H _(2) O + 2 HCl to 2 Na Cl + 4 H _(3) BO _(3) + 5 H _(2) O`
Methyl orange with pH value of 3.7 is used to detect end point. Aqueous solution of borax acts as buffer, because borax is salt is strong base `NaOH` and weak acid `H _(3) BO _(3).`