A carbon-13 NMR spectrum shows three distinct peaks at 20 ppm, 50 ppm, and 130 ppm. Identify the carbon environments represented by these peaks.

The peak at 20 ppm likely represents a methyl (–CH3) carbon, the peak at 50 ppm represents a carbon attached to an electronegative atom (like –O), and the peak at 130 ppm represents an aromatic carbon. This answer is anchored to NMR spectroscopy (A-level only).

The peak at 20 ppm likely represents a methyl (–CH3) carbon, the peak at 50 ppm represents a carbon attached to an electronegative atom (like –O), and the peak at 130 ppm represents an aromatic carbon. is the best answer because it directly supports the AQA A-Level Chemistry objective to use carbon-13 NMR spectra to identify carbon environments. This reasoning is anchored to NMR spectroscopy (A-level only) in Nuclear magnetic resonance spectroscopy (A-level only), and it separates NMR from similar A-Level ideas rather than relying on a vague recall statement. Other options are weaker if they use the wrong evidence, calculation, mechanism, observation, unit, or conclusion for this subtopic.