Acid rain is a worldwide environmental issue. You collect a sample of potentially acidic rainwater and submitted to analyze. Several acidic ions were found in the solutions and the concentrations were shown below: Total inorganic carbon = 0.1 mg-C/L [Cl-] = 0.7 mg/L as Cl [NO3-] = 0.6 mg/L as N [SO42-] = 0.5 mg/L as S (Note: TIC is the total concentration of carbon dioxide) Please calculate the pH value of the rainwater.