(A)Na2[B4O5(OH)4]−8H2O+2HCl→2NaCl+4H3BO3+5H2O(B)2BN+6H2O→2H3BO3+2NH3(C)H3BO3375k−H2OHBO2(Metaboricacid);4HBO2435k−H2OH2B4O7(tetraboricacid);H2B4O7redheat−H2O2B2O3(boricoxide)(D) H3BO3 is a weak monobasic acid as it liberates hydrogen ions as H3BO3→H++H2BO−3