Discussion
Why is chemical shift quoted in parts per million rather than hertz?
Answer: B
Dividing the shift in hertz by the spectrometer frequency in megahertz gives a dimensionless number independent of the field, so a proton at 7.2 ppm is at 7.2 ppm on a 300 and on a 600 MHz instrument. In hertz it would be 2160 on one and 4320 on the other, and no table of values could be shared. Coupling constants deliberately stay in hertz precisely because they do not scale with field, and the contrast between the two is a standard way of telling a coupling from a shift difference: run the sample at another field.
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