iGCSE Chemistry (0620) Core:12.3 Chromatography: Exam Style Questions Paper 1- New Syllabus
▶️ Answer/Explanation
Detailed solution:
Looking at the chromatogram, dye X has not moved from the baseline (origin), meaning it is insoluble in the solvent (ethanol)—it did not dissolve and therefore could not travel up the paper. So statement 2 is correct. The sweet S contains two spots: one that aligns with W and one that appears near the bottom. The spot aligning with W indicates S contains dye W, so statement 4 is correct. However, S does not contain dyes Y or Z, as there are no spots aligning with those positions—so statement 3 is incorrect. Statement 1 says S contains only two dyes, but the chromatogram may show additional components. Based on what we can see, statements 2 and 4 are correct, making option C the right choice.
▶️ Answer/Explanation
Detailed solution:
From the chromatogram, P shows more than one spot, so it’s a mixture, not pure. A spot from P lines up at the same height as a spot from Q, meaning they share a colour that travels the same distance in the solvent. The top line is the solvent front, not the baseline. R has some spots not present in Q, so D is false. Therefore, B is the correct statement.
▶️ Answer/Explanation
Detailed solution:
In paper chromatography, the paper must be set up so the baseline where the sample spots are placed is above the level of the solvent. If the solvent reaches the spots directly, the samples will simply dissolve straight into the bulk liquid instead of travelling up the paper. Diagram B correctly shows the solvent level sitting below the pencil baseline and the sample spots, which is the proper setup to allow the solvent to rise up the paper by capillary action and carry the components with it.