What is the representation of an electrochemical cell featuring a standard e.m.f. of 0.93 V?

The representation of an electrochemical cell describes the half-cell reactions occurring at the anode and cathode, as well as the standard electrode potentials associated with those reactions. The key to identifying the correct representation based on the given standard e.m.f. of 0.93 V involves recognizing the reduction potentials of the half-cells involved.

In the provided answer choice, the half-cell reactions at the anode are the oxidation of iron from iron(II) to iron(III), and at the cathode, the reduction of cerium from Ce(IV) to Ce(III). The standard electrode potentials for these half-reactions contribute to a net voltage of 0.93 V when combined appropriately under standard conditions.

This choice captures both the necessary chemical species and their relevant electrode potentials that, together, yield the stated e.m.f. When considering the overall cell potential, it is crucial that the half-reactions occur in a compatible manner, with one being an oxidation and the other a reduction, and this specific combination results in the desired e.m.f.

The other choices involve different metal ions and gas species that either do not yield the right voltage or do not align with standard reference values effectively enough to match 0.93 V. Hence,