In a paper chromatography experiment, four pigments (A, B, C, and D) are separated into distinct colored bands. If pigment A has the highest R_f value and pigment D has the lowest R_f value, which pigment corresponds to the band closest to the solvent front?

• A. Pigment B
• B. Pigment C
• C. Pigment D
• D. Pigment A

Answer: (D)

Verified step by step guidance

1. Understand that in paper chromatography, the R\_f value (retention factor) is defined as the ratio of the distance traveled by the pigment to the distance traveled by the solvent front, given by the formula: \[ R\_f = \frac{\text{distance traveled by pigment}}{\text{distance traveled by solvent front}} \]
2. Recognize that a higher R\_f value means the pigment traveled farther up the paper, closer to the solvent front, while a lower R\_f value means the pigment traveled less distance and is farther from the solvent front.
3. Given that pigment A has the highest R\_f value, it means pigment A traveled the greatest distance among the pigments and is therefore closest to the solvent front.
4. Conversely, pigment D has the lowest R\_f value, indicating it traveled the shortest distance and is farthest from the solvent front.
5. Thus, the band closest to the solvent front corresponds to pigment A, which matches the given information.