Some standard electrode potentials at 298 K are given below :

Pb²⁺ /Pb = $$- $$0.13 V

Ni²⁺ /Ni = $$-$$ 0.24 V

Cd²⁺ /Cd = $$-$$ 0.40 V

Fe²⁺ /Fe = $$-$$ 0.44 V

To a solution containing 0.001 M of X²⁺ and 0.1 M of Y²⁺, the metal rods X and Y are inserted (at 298 K) and connected by a conducting wire. This resulted in dissolution of X. The correct combination(s) of X and Y, respectively, is(are)

(Given : Gas constant, R = 8.314 J K^$$-$$ mol^$$-$$1, Faraday constant, F = 96500 C mol^$$-$$1)

In a galvanic cell, the salt bridge

For the reduction of NO$$_3^ - $$ ion in an aqueous solution, E$$^0$$ is + 0.96 V. Values of E$$^0$$ for some metal ions are given below:

$$\matrix{ {{V^{2 + }}(aq.) + 2{e^ - } \to V} & {{E^0} = - 1.19\,V} \cr {F{e^{3 + }}(aq.) + 3{e^ - } \to Fe} & {{E^0} = - 0.04\,V} \cr {A{u^{3 + }}(aq) + 3{e^ - } \to Au} & {{E^0} = + 1.40\,V} \cr {H{g^{2 + }}(aq) + 2{e^ - } \to Hg} & {{E^0} = + 0.86\,V} \cr } $$

The pair(s) of metals that is (are) oxidized by NO$$_3^ - $$ in aqueous solution is(are)