An alloy of chromel containing Ni,Fe & Cr was analysed by a complexometric titration using EDTA as the titrant. The solution of the alloy was prepared by dissolving 0.7176g of alloy in HNO3 and then diluted to mark in 250cm³ volumetric flask. 50cm³ of this aliquot of the sample was treated with pyrophosphate to mark the iron and chromium. If this aliquot of the sample require 26.14cm³ of 0.058M EDTA to reach the end point with murexide as the indicator. In a second titration 50cm³ aliquot treated with hexamethylenetetraamine to mask chromium require 35.43cm³ of 0.058M EDTA to reach the end point. Finally, a third 50cm³ of aliquot was treated 50cm³ of 0.058M EDTA and back titrated with 6.21cm³ of 0.063M Cu²+ yo reach the end point with murexide indicator. Calculate the percentage of Nickel, Iron and chromium in the alloy