A 1.00 gm sample of H₂O₂ solution containing X percent H₂O₂ by weight requires X ml of a KMnO₄ solution for complete oxidation under acidic conditions. Calculate the normality of the KMnO₄ solution.

(i). A sample of MnSO₄.4H₂O is strongly heated in air. The residue is Mn₃O₄.

(ii). The residue is dissolved in 100 ml of 0.1N FeSO₄ containing dilute H₂SO₄.

(iii). The solution reacts completely with 50 ml of KMnO₄ solution.

(iv). 25 ml of the KMnO₄ solution used in step (iii) requires 30 ml of 0.1 N FeSO₄ solution for complete reaction.

Find the amount of MnSO₄.4H₂O present in the sample.

A hydrocarbon contains 10.5 g of carbon per gram of hydrogen. 1 litre of the hydrocarbon at 127^oC and 1 atmosphere weighs 2.8 g. Find the molecular formula.

(a) One litre of a sample of hard water contains 1 mg of CaCl₂ and 1 mg of MgCl₂. Find the total hardness in terms of parts of CaCO₃ per 10⁶ parts of water by weight.

(b) A sample of hard water contains 20 mg of Ca⁺⁺ ions per litre. How many milli-equivalent of Na₂CO₃ would be required to soften 1 litre of the sample?

(c) 1 gm of Mg is burnt in a closed vessel which contains 0.5gm of O₂.
      (i) Which reactant is left in excess?
      (ii) Find the weight of the excess reactants.
      (iii) How many milliliters of 0.5N H₂SO₄ will dissolve the residue in the vessel?