In which of the following reactions H₂O₂ acts as a reducing agent?
1. H₂O₂ + 2H⁺ + 2e^- $$\to$$ 2H₂O
2. H₂O₂ - 2e^- $$\to$$ O₂ + 2H⁺
3. H₂O₂ + 2e^- $$\to$$ 2OH^-
4. H₂O₂ + 2OH^- - 2e^- $$\to$$ O₂ + 2H₂O

The equivalent conductance of NaCl at concentration C and at infinite dilution are $${\lambda _C}$$ and $${\lambda _\infty }$$, respectively. The correct relationship between $${\lambda _C}$$ and $${\lambda _\infty }$$ is given as: (where the constant B is positive)

For complete combustion of ethanol, C₂H₅OH(l) + 3O₂(g) $$\to$$ 2CO₂(g) + 3H₂O(l) the amount of heat produced as measured in bomb calorimeter, is 1364.47 kJ mol^–1 at 25^oC. Assuming ideality the Enthalpy of combustion, $$\Delta _CH$$, for the reaction will be : (R = 8.314 kJ mol^–1)

The ratio of masses of oxygen and nitrogen in a particular gaseous mixture is 1 : 4. The ratio of number of their molecule is: