we can use the dilution equation to find the volume of nitric acid needed to prepare a dilute solution
c1v1 = c2v2
c1 is concentration of concentrated solution and v1 is volume of concentrated solution
c2 is concentration of diluted solution and v2 is volume of diluted solution to prepared
substituting the equations
9.00 M x V = 1.25 M x 6.50 L
V = 0.903 L
903 mL of concentrated solution is required