The standard reduction potentials for Zn²⁺/Zn,Ni²⁺/Ni and Fe²⁺/Fe are –0.76,–0.23 and –0.44 V respectively.The reaction X + Y²⁺ ⟶ X²⁺ + Y will be spontaneous when

Resistance of 0.2M solution of an electrolyte is 50Ω. The specific conductance of the solution is 1.3 S m^-1. If resistance of the 0.4 M solution of the same electrolyte is 260 Ω, its molar conductivity is :

Consider the following cell reaction:
2Fe(s) + O₂(g) + 4H⁺(aq) 2Fe²⁺(aq) + 2H₂O(l); Eº = 1.67V
At[Fe²⁺] = 10^-3 M,p(O₂) = 0.1 atm and pH = 3, the cell potential at 25ºC is

The reduction potential of hydrogen half-cell will be negative if :

The correct order of E°_M²⁺/M values with negative sign for the four successive elements Cr, Mn, Fe and Co is

The Gibbs energy for the decomposition of Al₂O₃ at 500°C is as follows
\(\frac{2}{3}\)Al₂O₃ ⟶ \(\frac{4}{3}\)Al + O₂ , Δ_rG = +966 kJ mol^-1
The potential difference needed for electrolytic reduction of Al₂O₃ at 500°C is at least

In a fuel cell methanol is used as fuel and oxygen gas is used as an oxidizer. The reaction is
CH₃OH(l) + 3/2O(g) ⟶ CO₂(g)+2H₂O(l)
At 298 K standard Gibb’s energies of formation for CH₃OH(l),H₂O(l) and and CO₂ (g) are –166.2 –237.2 and –394.4 kJ mol^-1 respectively. If standard enthalpy of combustion of methonal is – 726 kJ mol^-1, efficiency of the fuel cell will be:

Given EºCr³⁺/Cr = –0.72 V, 2 Eº Fe²⁺/Fe = – 0.42 V. The potential for the cell Cr|Cr³⁺ (0.1M)|| Fe²⁺ (0.01 M)|Fe is