3.92 g of ferrous ammonium sulphate are dissolved in 100 ml water. 20ml of this solution requires 18 ml of potassium permaganate during titration for complete oxidation. The weight of KMnO4 present in one litre of the solution is

Mohr's salt is FeSO4.(NH4)2SO4.6H2OGMW of Mohr's salt = 392gn-factor Mohr's salt = 1(Fe+2 →Fe+3)GMW of KMnO4 = 158gn-factor KMnO4/H+ = 5(MnO4- →Mn+2 )I WMohr's salt = 3.92gVsol = 100ml 20ml of this solution required 18ml of KMnO4/H+ for complete oxidationGram equivalents of Mohr's Salt = Gram equivalents of KMnO4 H+VaNa = VbNb20(0.1)1 = 18(Mb)5                                                                                        = 3.511g