Discussion on A Question (H2, Chem, 2018, P2,Q5(a))

The following is the question.

This question is a very good question, which serves as a bridge between the items (electrochemistry) in syllabus and the application of the theories. But, I would like to discuss two points in this question from my view.

The first question is about the Q5(a)(i), and it involves the conception of reversible electrode. When the external voltage is less than the e.m.f of the cell, it will act as the a Galvanic Cell. When the external voltage is greater than the e.m.f of the cell, it will work as an electrolysis cell (or Electrolytic cell).  Moreover, it works similarly to the recharger cell (secondary cell).  To tell the truth, this question is very new to students, and it reminds teacher of the reversibility of the electrode.

However, in the next question Q5(a)(ii), the reaction occurs as equation 1, which is spontaneous as the standard cell potential is positive. So the cell should be electrochemistry cell, instead of the electrolysis cell. In the question, it states that 'The Clark Sensor ' is an electrolysis cell. Am I wrong or there is a bug in the question?

Looking forwards to the reply from the professionals who works with the Clark Sensor.

Thanks.