0.804 g sample of iron was dissolved in acid , Iron was reduced to `+2` state and it required 47.2 mL of 0.112 N `KMnO_4` solution for titration. Calculate the percentage of iron and `Fe_3O_4` in the ore.

0.592 g of calcium oxalate was dissolved in dilute acid and the solution was made up to 250 mL. 25 mL of this solution required 8.375 mL of 0.1 N KMnO_4 solution for complete oxidation. Calculate the percentage of calcium oxalate in calcium oxalate sample.

20 mL of a H_(2)O_(2) solution after acidification required 20 mL of N/10 KMn O_(4) solution for complete oxidation. Calculate the percentage and volume strength of H_(2)O_(2) solution.

A 2.76g impure sample of copper ore is dissolved and Cu^(2+) is titrated with KI solution. l_2 liberated required 40 mLof 0.1MNa_2S_2O_3 solution for titration. What is the % impurity present in the ore ?

0.35 g of an organic substance was Kjeldahlised and the ammonia obtained was passed into 100 ml of N/5 H_(2)SO_(4) . The excess acid required 154 ml of N/10 NaOH for neutralisation. Calculate the percentage of nitrogen in the compound.

1.15 g of an organic compound was analysed by Kjeldahl's method and the ammonia produced was collected in 30 mL of normal HCl solution. The excess of acid consumed 18.4 mL of normal sodium hydroxide solution for back titration. Calculate the percentage of nitrogen in the substance.

10 g of a sample of Ca(OH)_2 is dissolved in 10 mL of 0.5 N HCL solution . The excess of HCl was titrated with 0.2 N NaOH. The volume of NaOH used was 10 cc. Calculate the percentage of Ca(OH)_2 in the sample.

In the extraction of iron, Fe_(2)O_(3) is reduced with -

0.3 g of an oxalate salt was dissolved in 100 ml solution. The solution required 90 m! of N/20KMnO_4 for complete oxidation. The % of oxalate ion in salt is

0.05g of an organic compound was treated according to Kjedahl's method. Ammonia evoled was absorbed in 50ml of 0.05 (M) H_(2)S)_(4) . The residual acid required 60 ml 0.5 (M) solution of NaOH for neutralisation. Find the percentage composition of N in the compound.