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CBSE Class 12 Chemistry 2023 Delhi Set 1 Solved Paper

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Question : 4 of 35
Marks: +1, -0
Four half reactions I to IV are shown below:
I. 2Cl−→Cl2+2e−2 \mathrm{Cl}^{-} \rightarrow \mathrm{Cl}_2 + 2 e^{-}
II. 4OH−→O2+2H2O+2e−4 \mathrm{OH}^{-} \rightarrow \mathrm{O}_2 + 2 \mathrm{H}_2\mathrm{O} + 2 e^{-}
III. Na++e−→Na\mathrm{Na}^{+} + e^{-} \rightarrow \mathrm{Na}
IV. 2H++2e−→H22 \mathrm{H}^{+} + 2 e^{-} \rightarrow \mathrm{H}_2
Which two of these reactions are most likely to occur when concentrated brine is electrolysed?
Solution:     👈: Video Solution
Explanation:
At anode 2Cl−→Cl2+2e−2 \mathrm{Cl}^{-} \rightarrow \mathrm{Cl}_2 + 2 e^{-}
(2) At cathode
Na++e−→Na=Eo=−2.71 V\mathrm{Na}^{+} + e^{-} \rightarrow \mathrm{Na} = E_{o} = -2.71 \, \text{V}
2H++2e−→H2,Eo=0 V2 \mathrm{H}^{+} + 2 e^{-} \rightarrow \mathrm{H}_2, E_{o} = 0 \, \text{V}
Those have high EoE_{o} value, that reaction will take place.
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