The activity of component (i) can be written as (a) (a_{i}=frac{f_{i}^{0}}{f_{i}}) (b) (a_{i}=frac{f_{i}}{f_{i}^{0}}) (c) (a_{i}=ln left(frac{f_{i}}{f_{i}^{0}} ight))

The activity of component \(i\) can be written as

(a) \(a_{i}=\frac{f_{i}^{0}}{f_{i}}\)

(b) \(a_{i}=\frac{f_{i}}{f_{i}^{0}}\)

(c) \(a_{i}=\ln \left(\frac{f_{i}}{f_{i}^{0}}\right)\)

(d) \(a_{i}=\ln \left(f_{i}-f_{i}^{0}\right)\).