Final answer:
Absorbance measurements of 0.05 and 2.5 are considered inaccurate because they are outside the linear range of the instrument.
Step-by-step explanation:
Absorbance measurements of 0.05 and 2.5 are considered inaccurate because they are outside the linear range of the instrument. In a spectrophotometer, the instrument's response should be linearly proportional to the concentration of the absorbing species. However, beyond a certain range, the instrument may not accurately measure the absorbance. For example, if the concentration of the absorbing species is too low (0.05), the signal may be too weak to measure accurately. On the other hand, if the concentration is too high (2.5), the instrument may become saturated and unable to accurately measure the absorbance.