A-LevelChemistryAnalytical techniquesOct/Nov 2025Paper 4 Q67 Marks
(a) Thin-layer and gas/liquid chromatography can be used to separate mixtures into their individual components. (i) Define the following terms used in chromatography. Rf value retention time [2] (ii) Each type of chromatography makes use of a stationary phase and a mobile phase. Complete Table 6.1 with a description of each of these. [Table 6.1] [1] (b) A mixture of two substances A and B is analysed by thin-layer chromatography. The Rf value of substance A is larger than that of substance B. Suggest why substance A has a larger Rf value. [1] (c) The two isomeric compounds Y and Z are analysed by proton (1H) NMR spectroscopy. [Figure Y.Y] (i) Complete Table 6.2 to predict the number of peaks observed in the proton (1H) NMR spectra for Y and Z. [Table 6.2] [1] (ii) Name all the different splitting patterns observed in the proton (1H) NMR spectra for Y and Z. Y Z [2]
✓ Correct Answer
The correct answer is —. This question tests the candidate's understanding of analytical techniques within the Chemistrysyllabus. The examiner's mark scheme requires...
📋 Examiner Report & Trap Analysis
Common mistake: 62% of candidates selected the distractor because they confused... The examiner specifically designed this question to test whether students can differentiate between... To secure full marks, candidates must demonstrate...
🔒
Unlock the Examiner's Answer
Sign up for free to reveal the correct answer, the official mark scheme breakdown, and the examiner trap analysis for this question.
Sign Up Free to Unlock →Join thousands of Cambridge students already using Oracle Prep