Given

CO³⁺ + e^– $$ \to $$ CO₂⁺ ; E^o = + 1.81 V

Pb⁴⁺ + 2e^– $$ \to $$ Pb₂⁺ ; E^o = + 1.67 V

Ce⁴⁺ + e^– $$ \to $$ Ce³⁺ ; E^o = + 1.61 V

Bi³⁺ + 3e^– $$ \to $$ Bi ; E^o = + 0.20 V

Oxidizing power of the species will increase in the order :

The metal that gives hydrogen gas upon treatment with both acid as well as base is :

The integral $$\int {{{2{x^3} - 1} \over {{x^4} + x}}} dx$$ is equal to :
(Here C is a constant of integration)

For x $$ \in $$ (0, 3/2), let f(x) = $$\sqrt x $$ , g(x) = tan x and h(x) = $${{1 - {x^2}} \over {1 + {x^2}}}$$. If $$\phi $$ (x) = ((hof)og)(x), then $$\phi \left( {{\pi \over 3}} \right)$$ is equal to :