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.

Read the following statement and explanation and answer as per the options given below:

STATEMENT (S): In the titration of Na₂CO₃ with HCl using methyl orange indicator, the volume required at the equivalence point is twice that of the acid required using phenolphthalein indicator.

EXPLANATION (E): Two moles of HCl are required for the complete neutralization of one mole of Na₂CO₃

Arrange of the following in :
Increasing order of ionic size:
N^3-, Na⁺, F^-, O^2-, Mg²⁺