Task: Question Answering
Input (English): Question: A potentiometric titration is always done at i = 0: 
 Options:  <1> Yes, because that is where the Nernst equation is fulfilled. <2> Yes, because it is an instrumental requirement. <3> No, because there are potentiometric titrations at constant i. <4> No, because potentiometric titrations are never made at i = 0. <5> Yes, as long as an indicator electrode and a reference electrode are used.
Output (English): 3