A 1.0 g sample of Fe₂O₃ solid of 55.2% purity is dissolved in acid and reduced by heating the solution with zinc dust. The resultant solution is cooled and made upto 100.0 ml. An aliquot of 25.0 ml of this solution requires 17.0 ml of 0.0167M solution of an oxidant for titration. Calculate the number of electrons taken by the oxidant in the reaction of the above titration.

A solution of 0.2 g of a compound containing Cu²⁺ and $$C_2O_4^{2-}$$ ions on titration with 0.02M $$KMnO_4$$ in presence of $$H_2SO_4$$ consumes 22.6 ml. of the oxidant. The resultant solution in neutralized with Na₂CO₃, acidified with dil. acetic acid and treated with excess KI. The liberated iodine requires 11.3 ml of 0.05M Na₂S₂O₃ solution for complete reduction.

Find out the molar ratio of Cu²⁺ to $$C_2O_4^{2-}$$ in the compound.Write down the balanced redox reactions involved in the above titrations.

Calculate the molality of 1 litre solution of 93% H₂SO₄ (weight/volume). The density of the solution is 1.84 g/ml

A solid mixture (5.0 g) consisting of lead nitrate and sodium nitrate was headed below 600^oC until the weight of the residue was constant. If the loss in weight 28.0 percent, find the amount of lead nitrate and sodium nitrate in the mixture.