the balanced equation for the above reaction is as follows;
2Fe + 6HCl --> 2FeCl₃ + 3H₂
stoichiometry of Fe to HCl is 2:6
number of Fe moles reacted - 100.0 g/ 56 g/mol = 1.79 mol
if 2 mol of Fe reacts with 6 mol of HCl
then 1.79 mol of Fe reacts with - 6/2 x 1.79 = 5.37 mol
the number of HCl moles required are 5.37 mol
if 6.00 mol of HCl are in 1 L volume of HCl solution
then volume required for 5.37 mol are in - 5.37 mol / 6.00 mol/L = 0.895 L
therefore volume required is 895 mL