Electrode potential for `Mg` electrode varies according to the equation
`E_(Mg^(2+)|Mg)=E_(Mg^(2+)|Mg)^(ϴ) -(0.059)/2 "log" 1/([Mg^(2+)])`
The graph of `E_(Mg^(2+)|Mg) vs log [Mg^(2+)]` is