Acids have ph less than 7 and alkali have ph more than 7
The initial concentration of solution is 0.0693 M. The volume of solution taken is 10 mL and it is diluted to a final volume of 500 mL.
According to dilution law, the product of initial concentration and volume is equal to the product of final concentration and volume as follows:

Here,
is initial concentration,
is final concentration,
is initial volume and
is final volume.
Rearranging to calculate final concentration,

Putting the values,

Therefore, concentration of the resulting solution is 0.001386 M.
Fe: 2 x 55.845 = 111.69
O: 3 x 15.9994= 47.9982
111.69 + 47.9982 = 159.69 g/mol