Answer
See explanation.
Work Step by Step
a. This is done in example 41.6, at the top of page 1382. The energy is of this state is lowered.
$$U=-(9.285\times10^{-24}J/T)(1.60T)=-1.486\times10^{-23}J$$
$$=-9.29\times10^{-5}eV$$
b. Since n=1, $l=0$. In the 1s state there is no orbital magnetic dipole interaction. For larger values of n, there can be nonzero values of $l$, and yes, then there could be an orbital magnetic dipole interaction.
