a) mu= g*mu_n*I/h_bar, so g=mu*h_bar/(mu_n*I). With mu = -0.594 mu_n and I= 1/2, g =-1.188*h_bar for the ground state.
For 245keV, With mu = -0.766 mu_n and I= 5/2, g =-0.3064*h_bar
b) Now J=1/2, so g= 2mu_b*h_bar/mu_n.
c) Now J=1/2 and g = -3.826, so mu=7.652*mu_n/h_bar.