To determine the concentration of iron II sulfate in a given solution using spectrophotometry, you will need to follow these steps:1. Prepare a series of standard solutions with known concentrations of iron II sulfate. You can do this by dissolving a known mass of iron II sulfate in a known volume of solvent usually water .2. Measure the absorbance of each standard solution at the wavelength of 400 nm using a spectrophotometer. Make sure to measure the absorbance of the solvent blank as well to subtract it from the absorbance of the standard solutions.3. Plot a calibration curve by graphing the absorbance values y-axis against the known concentrations of iron II sulfate x-axis . The relationship between absorbance and concentration should be linear, according to the Beer-Lambert Law: A = bc, where A is absorbance, is the molar absorptivity, b is the path length, and c is the concentration.4. Determine the equation of the best-fit line for the calibration curve. This equation will be in the form of y = mx + b, where y is the absorbance, x is the concentration, m is the slope, and b is the y-intercept.5. Measure the absorbance of the unknown iron II sulfate solution at 400 nm using the spectrophotometer. Make sure to subtract the absorbance of the solvent blank from the absorbance of the unknown solution.6. Use the equation of the best-fit line from the calibration curve to calculate the concentration of iron II sulfate in the unknown solution. Plug the absorbance value of the unknown solution into the equation as y and solve for x, which represents the concentration.For example, if the equation of the best-fit line is y = 2x + 0.1 and the absorbance of the unknown solution is 0.5, you would solve for x as follows:0.5 = 2x + 0.10.4 = 2xx = 0.2In this example, the concentration of iron II sulfate in the unknown solution would be 0.2 M or mol/L .