You can analyze for a copper compound in water using an instrument called a spectrophotometer. [A spectrophotometer is a scientific instrument that measures the amount of light (of a given wavelength) that is absorbed by the solution.] The amount of light absorbed at a given wavelength of light (A) depends directly on the mass of compound per liter of solution. To calibrate the spectrophotometer, you collect the following data 

Plot the absorbance (A) against the mass of copper compound per liter (g/L), and find the slope (m) and intercept (b) (assuming that A is y and the amount in solution is x in the equation for a straight line, y = mx + b). What is the mass of copper compound in the solution in g/L and mg/mL when the absorbance is 0.635?

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Absorbance (A) 0.000 0.257 0.518 0.771 1.021 Mass per Liter of Copper Compound (g/L) 0.000 1.029 x 10-3 2.058 x 10-3 3.087 x 10-3 4.116 x 10-3