Following are a list of possible errors that can occur in the analysis of a substance. a) A weight is obtained from an incorrectly calibrated balance. b) The volume reading of a Mohr pipet is read incorrectly when transferring an aliquot of the analytical reagent used in the analysis. c) A non-representative sample of an inhomogeneous material is taken for the analysis. d) The control sample used to calibrate the analytical reading was made incorrectly. e) Stray light in the spectrophotometer produces an error in the absorbance reading of the sample.