Directions : In the following question more than one of the answers given may be correct. Select the correct answer and mark it according to the code:
Given, \[E_{(N{{i}^{2+}}/Ni)}^{o}=0.25\,V,E_{(C{{u}^{2+}}/Cu)}^{o}=0.34\,V;\] \[E_{(A{{g}^{+}}/Ag)}^{o}=0.80\,V\] and \[E_{(Z{{n}^{2+}}/Zn)}^{o}=-0.76\,V;\] Which of the following reactions under standard condition will not take place in the specified direction? (1) \[N{{i}^{2+}}+Cu\xrightarrow[{}]{{}}Ni+C{{u}^{2+}}\] (2) \[Cu+2A{{g}^{+}}\xrightarrow[{}]{{}}C{{u}^{2+}}+2Ag\] (3) \[Cu+2{{H}^{+}}\xrightarrow[{}]{{}}C{{u}^{2+}}+{{H}_{2}}\] (4)\[Zn+2{{H}^{+}}\xrightarrow[{}]{{}}Z{{n}^{2+}}+3{{H}_{2}}\]A) 1, 2 and 3 are correct
B) 1 and 2 are correct
C) 2 and 4 are correct
D) 1 and 3 are correct
Correct Answer: D
Solution :
For reaction (1), \[E_{cell}^{o}=0.25-(0.34)\] \[=-0.09V\] For reaction (2), \[E_{cell}^{o}=0.80-(0.34)\] \[=0.46V\] For reaction (3), \[E_{cell}^{o}=0-(0.34)\] \[=-0.34V\] For reaction (4), \[E_{cell}^{o}=0-(0.76)\] \[=0.76V\] Hence, reaction (1) and (3) will not take place as\[E_{cell}^{o}=-ve\].
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