g-factor given by g=(µ*hbar)/(µN*I) with µ magnetic dipole moment and I the spin.
1a.1) g = (-0.5940*hbar)/(µN*(1/2))
1a.2) g = (-0.766*hbar)/(µN*(5/2))
muB given by µB = (e*hbar)/(2*me) and g = (2*m*µ)/(e*S). The g-factor becomes:
1b) g = (µ/S)*(hbar/µB) = hbar/(1/2) = 2*hbar