Final Answer:
The hydrogen that gives the signal at 1.8 ppm is H1.
Therefore, option a) H1 is correct.
Step-by-step explanation:
In nuclear magnetic resonance (NMR) spectroscopy, the chemical shift is a measure of the magnetic environment of a nucleus. The hydrogen signal at 1.8 ppm corresponds to the chemical shift of H1.
This means that the NMR spectrum shows a peak at 1.8 ppm, specifically due to the hydrogen atom labeled as H1.
Interpreting NMR spectra is a crucial skill in organic chemistry, allowing chemists to deduce the structure of organic compounds. Chemical shifts provide information about the local electronic environment of nuclei, aiding in the identification and characterization of molecules.
Therefore, option a) H1 is correct.