a) M NH4Cl=14g/mol+4*1 g/mol+35,5 g/mol=53,5 g/mol
b) M Ca(OH)2=40 g/mol+2*16 g/mol+2*1 g/mol=74 g/mol
c) M MgSO4*7H2O=24 g/mol+32 g/mol+4*16 g/mol+7*18 g/mol=246 g/mol