Data misinterpretation based on personal bias happens more often than an elucidator likes to admit. The purpose of this puzzle is to examine a potential pitfall while interpreting data from a 2D NMR spectrum.
For an unknown compound, the 1H -13C HMQC spectrum below shows two correlations both of which are assigned to the same carbon shift at 126 ppm. The 1H integral information shows the correlations to be 1 Hydrogen atom each. Is the 13C at 126 ppm a CH2?