standardizing the sodium hydroxide against potassium hydrogen phthalate which of the following best explains why weighing by difference eliminates systematic balance errors? a. weighing by difference requires subtracting the final mass of the sample container from the initial mass of the sample container. b. consider this aspect of the measurement when you select your answer. c. finger smudges will evaporate between weighings. d. because the mass is determined by the difference between two readings, a systematic error in the absolute mass on the balance will be removed by subtracting the final weight from the initial weight. e. air currents that may support the sample are eliminated. f. none of the above.