NMR spectroscopy

Mass of the proton is nearly 1837 times heavies than the mass of electron and hence the electronic magnetic moment is greater that the nuclear magnetic moment by this ratio.

It is not true, electrons play no role in NMR, conversely they are paramount because the main information we obtain in a NMR spectrum is the chemical shift that comes directly for the effects of the electron density on the nucleus.

The magnetic field the nucleus experiences differs slightly from the applied field, $B_0$ , because the magnetic field at the nucleus is shielded by the electron density surrounding the nucleus. This shielding is due to precession of electrons under the influence of the applied magnetic field. This precession generates an additional magnetic field that usually opposes the externally applied magnetic field. The local magnetic field strength at the nucleus is given by:

$B = (1 - sigma) · B_0$

As the electron density around the nucleus increases, the effective field decreases, leading to lower resonance frequencies. Since the resonance frequency is due to the chemical environment of the nuclear spin, the observed frequency is referred to as a chemical shift.