$\begin {array} {1 1} (A)\;Na_2[B_4O_5(OH)_4]-8H_2O+2HCl \rightarrow 2NaCl+4H_3BO_3+5H_2O \\ (B)\;2BN+6H_2O \rightarrow 2H_3BO_3+2NH_3 \\ (C)\;H_3BO_3 \large\frac{ 375k}{-H_2O}HBO_2 (Metaboric \: acid) ; 4HBO_2 \large\frac{435k}{-H_2O}H_2B_4O_7 (tetraboric\: acid); H_2B_4O_7 \large\frac{red \: heat}{-H_2O} 2B_2O_3 (boric \: oxide) \\ (D)\;\text{ $H_3BO_3$ is a weak monobasic acid as it liberates hydrogen ions as $H_3BO_3 \rightarrow H^+ + H_2BO_3^-$} \end {array}$
