The standard EMF of a Zn|Zn²⁺||Cu²⁺|Cu cell (E°_Cu²⁺/Cu = +0.34 V; E°_Zn²⁺/Zn = −0.76 V) is
A{'text': '+1.10 V', 'label': 'A'}
B{'text': '+0.42 V', 'label': 'B'}
C{'text': '−1.10 V', 'label': 'C'}
D{'text': '−0.42 V', 'label': 'D'}
Answer & Solution
Correct answer: A. {'text': '+1.10 V', 'label': 'A'}
1. Daniell cell: Zn (anode, oxidation), Cu (cathode, reduction).
2. E°_cell = E°_cathode − E°_anode = 0.34 − (−0.76) V.
3. E°_cell = 0.34 + 0.76 = +1.10 V.
4. Positive value means the reaction is spontaneous as written.
_Source: NCERT Class 12 Chemistry, Unit 3 "Electrochemistry", §3.2_
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