Boric acid `B(OH)_(3)` is weak monobasic acid reacts with alkali to form borates. The most common borate of boric acid is borax represented as `Na_(2)(B_(4)O_5(OH)_4.8H_2O` which is made up of two tetrahedral and two triangular units. On dissolution in water, these tetrahedral and triangular units are seperated. Borax is useful primary standard for titra tion against acids 
The number of B - O - B linkage in borax is/are

Options

A. All proportions of the above mixing would result in an neutral solution having `pH =7 at 25^(@) C `
B. If aq. `NH_3` is exactly half neutralized by HCl, then pOH of resulting solution is equal to `pK_a`
C. If acetic acid is exactly half neutralized by NaOH, then pH of resulting solutions is equal to `pK_a`
D. If acetic acid is exactly neutralized by aq. `NH_3` then pH of resuling solution is equal `1//2` pkw

Answer

B, C, D

Explanation

on complete neutralization `CH_3 COONH_4 ` is formed and pH ` = ((7 +pKa - pKb)/( 2)) = 7 (pKu)/(2)`
(b) At half neutralisation , buffer
` pOH =pKb + log ""(S)/(B) = pKb`
( c ) At half neutralisation buffer
` pH =pKa + log ""(S)/(A) = pKa`