A water sample at 25 "C presents the following chemical characteristics: Ar=0 mg/L CaCO, Au-75 mg/L CaCO, Acidity=2 meq/L Ca"-60 mg/L Mg 36 mg/L The stability index according to Langeler is -0.15. Calculate: 1) The pH of the water 2) The aggressive CO, 3) The calcium carbonate hardness K,-4.47x107 Atomic weight: H-1, 0-16, Ca-40, Mg-24, C-12