Identify the correct statement(s) regarding ultraviolet-visible spectrophotometry:
(A) Substances appear coloured due to the absorption of some wavelengths of light and transmission of other wavelengths.

(B) The absorption of radiation is described by the Beer-Lambert law: A=ϵcl.

(C) Compounds with high values of ϵ\epsilonϵ, the molar absorption coefficient, absorb high intensities of light at a given concentration ccc.

(D) The absorbance of a solution is proportional to its concentration c.

(E) The absorbances of several species in solution are additive so that the mixtures of compounds can be analyzed.

Correct option is D

Information Booster:
1. (a) Substances appear coloured due to selective absorption: This is correct as visible spectrophotometry measures how substances absorb certain wavelengths of light while transmitting others, making them appear coloured.
2. (b) Beer-Lambert Law: Absorbance (AAA) is described by A=ϵcl, where ϵ is the molar absorptivity, c is the concentration, and l is the path length.
3. (c) Role of molar absorptivity: A higher molar absorption coefficient (ϵ) corresponds to greater absorption at specific wavelengths, especially for coloured or UV-active compounds.
4. (d) Proportionality of absorbance to concentration: According to Beer-Lambert law, absorbance is directly proportional to the concentration of the absorbing species.
5. (e) Additivity of absorbances: In mixtures, the total absorbance at a specific wavelength is the sum of the absorbances of individual components.
Hence, all the statements are correct.
Information Booster: 1. Beer-Lambert Law: It applies only under conditions of monochromatic light, dilute solutions, and non-scattering systems.
2. Applications:
· Quantitative determination of substances in a mixture.
· Detection of conjugated compounds and proteins.
3. Limitations: High concentrations may deviate due to scattering and changes in ϵ\epsilonϵ.
4. Additivity Principle: A mixture of species obeys: Atotal=A1+A2+…+An.
Additional Knowledge: · (a): Refers to the colour we perceive due to selective absorption of visible light.
· (b): Beer-Lambert law works efficiently in solutions with a fixed path length.
· (c): The molar absorption coefficient ϵ\epsilonϵ indicates how strongly a substance absorbs light.
· (d): As concentration increases, absorbance rises linearly, provided the solution remains clear.
· (e): In UV-visible spectrophotometry, overlapping spectra can be resolved by using the additivity property.