A'H NMR signal is observed at 166.0 Hz (downfield of TMS) on a 155-MHz instrument. a) What is the observed chemical shift in parts per million (ppm)? Chemical shift is ppm b) What is the chemical shift, in parts per million (ppm), if the sample is analyzed with a 300.0-MHz instrument? Chemical shift is ppm c) Where will the proton signal appear, in hertz, if the sample is analyzed with a 300.0-MHz instrument? The downfield signal is Hz