a) Immediately after closing switch, the current in the inductor is zero.
b) After a long time, the inductor is fully energized; with the current no longer changing, the emf across the inductor is zero. In effect the inductor can be replaced by a zero-ohm wire for the purpose of circuit analysis for a long time after switch closure. Solve the resulting multiloop circuit for the currents.
c) i1 = 0 immediately on the switch opening (there is no inductance indicated in that branch). The rightmost branch with the inductor is going to keep the same value of current that it had just before the switch was opened.
d) The power source has been removed and there is dissipation in the circuit.