LET THE NUMBER OF Fe3+ IONS BE X THEN, NO. OF Fe2+ IONS= 0.93-X
NOW ,
OXIDATION STATE OF Fe IS +2.
=> 3X+2(0.93-X) = 2
=> 3X+1.86-2X = 2
=>X = 2-1.86
=>X = 0.14
NUMBER OF ATOMS OF Fe3+ IONS IS 0.14
%AGE OF Fe3+ = (0.14/0.93)*100
=15.05%
RATE ME IS MY ANSWER IS SATISFACTORY..