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NEET Sample Paper NEET Sample Test Paper-18

  • question_answer
    If the half-cell reactions are given as
    (i)\[F{{e}^{2+}}+2e\to Fe(s);{{E}^{o}}=-0.44\,V.\]
    (ii)\[2{{H}^{+}}(aq)+\frac{1}{2}{{O}_{2}}(g)+2e\to {{H}_{2}}O(l);{{E}^{o}}=+1.23\,V.\]
    The \[E{}^\circ \] for the reaction \[Fe\,(s)+2{{H}^{+}}+\frac{1}{2}{{O}_{2}}(g)\to F{{e}^{2+}}(aq)+{{H}_{2}}O(l)\]

    A) \[-0.79\,V\]                  

    B) \[-1.67\,V\]

    C) \[1.67\,V\]                   

    D) \[0.79\,V\]   

    Correct Answer: C

    Solution :

    Subtracting equation (i) from (ii) we get equation 3 as follows: \[Fe\,(s)+2{{H}^{+}}+1/2{{O}_{2}}\to F{{e}^{2+}}(aq)+{{H}_{2}}O(l)\]     (3) So, \[{{E}^{o}}={{E}^{o}}_{2}-{{E}^{o}}_{1}\] \[=+1.23-(-0.44)\] \[=+1.67\,V\] Hence, the correct option is [c].


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