8 7.4 Activity and activity coefficient 3. Influential factors 1)Concentration-dependence Discussion HCI 1.0 Nacl 0.8 0.6 Mg(NO3 )2 0.4 0.2 ZnsO4 00.10.20.30.40.50.6 m/ mol kg-I3. Influential factors 1) Concentration-dependence Discussion: 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.0 0.2 0.4 0.6 0.8 1.0 HCl NaCl Mg(NO3 ) 2  m / mol·kg-1 ZnSO4 §7.4 Activity and activity coefficient