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