Identify the incorrect statement from the options below for the above cell:

$$E^0_{Cu^{2+}|Cu} = +0.34$$ V,
$$E^0_{Zn^{2+}|Zn} = -0.76$$ V

The cell under discussion is the Daniell cell

$$\text{Zn} \,|\, \text{Zn}^{2+}(aq) \;||\; \text{Cu}^{2+}(aq) \,|\, \text{Cu}$$

Standard electrode potentials (all in volts) are

$$E^{0}_{\text{Cu}^{2+}|\text{Cu}} = +0.34,$$ $$E^{0}_{\text{Zn}^{2+}|\text{Zn}} = -0.76$$

Standard cell emf

$$E^{0}_{\text{cell}} = E^{0}_{\text{cathode}} - E^{0}_{\text{anode}} = 0.34 -(-0.76) = 1.10 \text{ V}$$

In the spontaneous (galvanic) mode:
  • Zn is oxidised: $$\text{Zn} \rightarrow \text{Zn}^{2+} + 2e^-$$ (anode).
  • Cu2+ is reduced: $$\text{Cu}^{2+} + 2e^- \rightarrow \text{Cu}$$ (cathode).
  • Electrons flow from Zn to Cu through the external circuit.

Now an external opposing voltage $$E_{\text{ext}}$$ is applied across the cell. Three situations arise:

$$E_{\text{ext}} \lt 1.10 \text{ V}$$ — The applied voltage is too small to overcome the cell’s own emf, so the spontaneous galvanic action continues.
  • Zn keeps dissolving (anode).
  • Cu keeps depositing (cathode).
  • Electrons still move from Zn to Cu.
This matches statement C, so C is correct.

$$E_{\text{ext}} = 1.10 \text{ V}$$ — The external voltage exactly balances the cell emf; net emf becomes zero.
  • No current flows, no redox change occurs.
This matches statement D, so D is correct.

$$E_{\text{ext}} \gt 1.10 \text{ V}$$ — The applied voltage now exceeds the cell emf and forces the reverse (electrolytic) reaction.
  • Cu is oxidised: $$\text{Cu} \rightarrow \text{Cu}^{2+} + 2e^-$$ at the Cu electrode (now the anode).
  • Zn2+ is reduced: $$\text{Zn}^{2+} + 2e^- \rightarrow \text{Zn}$$ at the Zn electrode (now the cathode).
  • Electrons are driven from Cu to Zn in the external circuit.

Hence for $$E_{\text{ext}} \gt 1.10 \text{ V}$$ we have “Cu dissolves and Zn deposits,” not the reverse.

Let us test each option:

Option A: “If $$E_{\text{ext}} \gt 1.1$$ V, $$e^-$$ flow from Cu to Zn.” — True (see Case 3).

Option B: “If $$E_{\text{ext}} \gt 1.1$$ V, Zn dissolves at Zn electrode and Cu deposits at Cu electrode.” — False; the opposite happens (Zn is deposited, Cu dissolves).

Option C: “If $$E_{\text{ext}} \lt 1.1$$ V, Zn dissolves at anode and Cu deposits at cathode.” — True (see Case 1).

Option D: “If $$E_{\text{ext}} = 1.1$$ V, no flow of $$e^-$$ or current occurs.” — True (see Case 2).

Therefore the incorrect statement is
Option B which is: If $$E_{\text{ext}} \gt 1.1$$ V, Zn dissolves at Zn electrode and Cu deposits at Cu electrode.