Identify factor(s) that cause the Beer's law relationship to be nonlinear: (A) Polychromatic radiation (B) Unknown chemical changes such as association or dissociation reactions (C) Stray light (D) Molecular or ionic interactions at high concentration
Choose the correct answer from the options given below:

Correct option is D

Beer–Lambert Law states:
A =ε⋅c⋅l
Where:
· A = Absorbance
· ε = Molar absorptivity
· c = Concentration
· l = Path length
For the relationship to remain linear, several ideal conditions must be met. The following factors cause nonlinearity:
· (A) Polychromatic radiation:
· Beer’s law assumes monochromatic light. Polychromatic (multiple wavelengths) causes deviation.
· (B) Chemical changes (association/dissociation):
· If the absorbing species changes due to chemical reactions, the absorbance no longer follows the law.
· (C) Stray light:
· Light outside the intended wavelength enters the detector, reducing apparent absorbance, especially at higher concentrations.
· (D) Molecular or ionic interactions at high concentration:
· Causes changes in molar absorptivity (ε) due to electrostatic interactions or aggregation, making the response nonlinear.
Information Booster:
· Ideal Beer’s law conditions: Dilute solution, no chemical reactions, monochromatic light, no stray light.
· Nonlinearity is especially noticeable at high concentrations or improper instrument calibration.