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NEET-XII-Chemistry

c2022 year:2022

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  • #9
    At `` 298\, K `` , the standard electrode potentials of `` Cu ^{2+} /Cu , Zn ^{2+} / Zn , Fe ^{2+} / Fe `` and `` Ag ^{+} / Ag `` are `` 0.34\, V `` , `` -0.76 \,V ,-0.44 \,V `` and `` 0.80 \,V `` , respectively. On the basis of standard electrode potential, predict which of the following reaction can not occur?

    (A) `` 2 CuSO _{4}( aq )+2 Ag ( s ) \rightarrow 2 Cu ( s )+ Ag _{2} SO _{4}( aq ) ``
    (B) `` CuSO _{4}( aq )+ Zn ( s ) \rightarrow ZnSO _{4}( aq )+ Cu ( s ) ``
    (C) `` CuSO _{4}( aq )+ Fe ( s ) \rightarrow FeSO _{4}( aq )+ Cu ( s ) ``
    (D) `` FeSO _{4}( aq )+ Zn ( s ) \rightarrow ZnSO _{4}( aq )+ Fe ( s ) ``
    digAnsr:   A
    Ans : SRP : `` E _{ Zn ^{2+} / Zn }^{\circ}< E _{ Fe ^{2+} / Fe }^{\circ}< E _{ Cu ^{2+} / Cu }^{\circ}< E _{ Ag ^{+} / Ag }^{\circ} ``
    Reactivity order : `` Zn > Fe > Cu > Ag ``
    In case of displacement reaction, more reactive metals (lower SRP) can displace less reactive metals (higher SRP) from their salt solution.
    `` CuSO _{4(\text { aq. })}+2 Ag _{( s )} \rightarrow Cu _{( s )}+ Ag _{2} SO _{4(\text { aq. })} ``
    Option (3)
    Reaction is not possible
    as `` Ag `` is less reactive metal compare to `` Cu `` .