NEET Sample Paper NEET Sample Test Paper-41

  • question_answer
    Standard electrode potentials are:
    \[F{{e}^{2+}}/Fe\]     \[E{}^\circ =-0.44V\]
    \[F{{e}^{3+}}/F{{e}^{2+}}\],           \[E{}^\circ =+0.77V\]
    \[F{{e}^{2+}},F{{e}^{3+}}\]and Fe bloks are kept together, then:

    A) \[F{{e}^{3+}}increases\]

    B) \[F{{e}^{3+}}decreases\]

    C) \[F{{e}^{2+}}/F{{e}^{3+}}remains\text{ }unchanged\]

    D) \[F{{e}^{2+}}\ decreases\]

    Correct Answer: B

    Solution :

    For the emf to be positive/ the following half-cell reaction will occur. \[\operatorname{Fe}\to F{{e}^{2+}}+2{{e}^{-}}, E{}^\circ =+0.44V\] \[2F{{e}^{3+}}+2{{e}^{-}}\to 2F{{e}^{2+}},\,\,{{E}^{o}}=+0.77V\] Overall reaction: \[\operatorname{Fe}+2F{{e}^{3+}},\to 3F{{e}^{2+}}, E{}^\circ \,cell=0.121V\] \[\operatorname{Hence} F{{e}^{3+}} will decrease\]


You need to login to perform this action.
You will be redirected in 3 sec spinner