PrepBharat

1.Standard electrode potential for Sn⁴⁺ / Sn²⁺ couple is + 0.15 V and that for the \[Cr^{3+}/Cr\] couple is – 0.74 V. These two couples in their standard state are connected to make a cell. The cell potential will be :
a) + 1.19 V
b) + 0.89 V
c) + 0.18 V
d) + 1.83 V

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2. If the E°cell for a given reaction has a negative value, then which of the following gives the correct relationships for the values of \[\triangle G^{\circ}\] and \[K_{eq}\] ?
a) \[\triangle G^{\circ}>0: K_{eq} >1\]
b) \[\triangle G^{\circ}< 0: K_{eq} >1\]
c) \[\triangle G^{\circ}<0: K_{eq} < 1\]
d) \[\triangle G^{\circ}>0: K_{eq} <1\]

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3. A solution contains \[Fe^{2+},Fe^{3+}\]  and \[I^{-}\] ions. This solution was treated with iodine at 35°C. E° for \[Fe^{3+}/Fe^{2+}\]   is + 0.77 V and E° for \[I_{2}/2I^{–} = 0.536 V.\]    The favourable redox reaction is :
a) \[I_{2}\] will be reduced to \[I^{-}\]
b) There will be no redox reaction
c) \[I^{-}\] will be oxidised to \[I_{2}\]
d) \[Fe^{2+}\] will be oxidised to \[Fe^{3+}\]

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4. Limiting molar conductivity of \[NH_{4}OH\]
\[ i.e.,\wedge^{\circ}_{m\left(NH_{4}OH\right)}\]     is equal to :
a) \[\wedge^{\circ}_{m\left(NH_{4}Cl\right)}+\wedge^{\circ}_{m\left(NaCl\right)}-\wedge^{\circ}_{m\left(NaOH\right)}\]
b) \[\wedge^{\circ}_{m\left(NaOH\right)}+\wedge^{\circ}_{m\left(NaCl\right)}-\wedge^{\circ}_{m\left(NH_{4}Cl\right)}\]
c) \[\wedge^{\circ}_{m\left(NH_{4}OH\right)}+\wedge^{\circ}_{m\left(NH_{4}Cl\right)}-\wedge^{\circ}_{m\left(HCl\right)}\]
d) \[\wedge^{\circ}_{m\left(NH_{4}Cl\right)}+\wedge^{\circ}_{m\left(NaOH\right)}-\wedge^{\circ}_{m\left(NaCl\right)}\]

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5. Standard reduction potentials of the half reactions are given below :
\[F_{2}\left(g\right)+2e^{-}\rightarrow 2F^{-}\left(aq\right);E° = + 2.85 V\]
\[Cl_{2}\left(g\right)+2e^{-}\rightarrow 2Cl^{-}\left(aq\right);E° = + 1.36 V\]
\[Br_{2}\left(l\right)+2e^{-}\rightarrow 2Br^{-}\left(aq\right);E° = + 1.06 V\]
\[I_{2}\left(s\right)+2e^{-}\rightarrow 2I^{-}\left(aq\right);E° = + 0.53 V\]
The strongest oxidising and reducing agents respectively are :
a) \[F_{2}\] and \[I^{-}\]
b) \[Br_{2}\] and \[Cl^{-}\]
c) \[Cl_{2}\] and \[Br^{-}\]
d) \[Cl_{2}\] and \[I_{2}\]

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6. Molar conductivities ( \[\wedge^°_m\] ) at infinite dilution of NaCl, HCl and \[CH_{3}COONa\]    are 126.4, 425.9 and 91.0 S \[cm^{2}mol^{-1}\]   respectively. \[\wedge^°_m\] for CH₃COOH will be :
a) 425.5 S \[cm^{2}mol^{-1}\]
b) 180.5 S \[cm^{2}mol^{-1}\]
c) 290.8 S \[cm^{2}mol^{-1}\]
d) 390.5 S \[cm^{2}mol^{-1}\]

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7. A hydrogen gas electrode is made by dipping platinum wire in a solution of HCl of pH = 10 and by passing hydrogen gas around the platinum wire at one atm pressure. The oxidation potential of electrode would be ?
a) 0.59 V
b) 0.118 V
c) 1.18 V
d) 0.059 V

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8. At 25°C molar conductance of 0.1 molar aqueous solution of ammonium hydroxide is 9.54 \[ohm^{-1} cm^{2}mol^{-1}\]    and at infinite dilution its molar conductance is 238 \[ohm^{-1} cm^{2}mol^{-1}\]    . The degree or ionisation of ammonium hydroxide at the same concentration and temperature is :
a) 20.800%
b) 4.008%
c) 40.800%
d) 2.080%

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9. A button cell used in watches functions as following
\[Zn(s) + Ag_{2}O(s) + H_{2}O(l) \rightleftharpoons 2Ag(s) + Zn^{2+}(aq) + 2OH^{-}(aq)\]
if half cell potentials are:
\[Zn^{2+}\left(aq\right)+2e^{-}\rightarrow Zn\left(s\right);E^{\circ} = – 0.76 V\]
\[Ag_{2}O\left(s\right)+H_{2}O(l) +2e^{-}\rightarrow 2Ag\left(s\right)+2OH^{-}\left(aq\right);E^{\circ} = 0.34 V\]
The cell potential will be :
a) 0.42 V
b) 0.84 V
c) 1.34 V
d) 1.10 V

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10. Conductivity (unit Siemen’s S) is directly proportional to area of the vessel and the concentration of the solution in it and is inversely proportional to the length of the vessel then the unit of the constant of proportionality is
a) S m \[mol^{-1}\]
b) \[Sm^{2} mol^{-1}\]
c) \[S^{-2}m^{2} mol\]
d) \[S^{2}m^{2} mol^{-2}\]

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