Q4. In Experimental Procedure, Part A.3.: The blank solution used to calibrate the spectrophotometer is 10.0mL of 0.2MFeNONO3)3 diluted to 25.0mL with 0.1M HNO3. Why is this solution preferred to simply using de-ionized water for the calibration? All of the above Because the blank should include all the chemical species except the unknown to correct for their possible absorbances: Because water can have a higher absorbance at the experiment's wavelength Because the acid is needed for the reaction to occur