<prompt> Equilibrium potential for an ion is calculated using:Gibbs-Donnan equationNerst equationGoldman equationNone  <response>: B i.e. Nernst equation Equilibrium potential i.e., membrane potential at which equilibrium bw concentration electrical gradient exist for any one univalent ion is calculated by Nernst equationQ and for several different ions by Goldmann- Hodgkin-katz equation. 