4.9 g of K2Cr2O7 is taken to prepare 0.1 L of the solution 10 mL of this solution is further taken to oxidize Sn2+ ion into Sn4+ ion Sn4+ so produced is used in second reaction to prepare Fe3+ ion then the millimoles of Fe3+ ion formed will be (assume all other components are in sufficient amount) [Molar mass of K2Cr2O7 = 294 g].