Question

can we apply kirchhoff's circuit laws to AC?

Answer 1

http://openstudy.com/study#/updates/4fd05596e4b0e0466317f727

Answer 2

In practice, yes, you can apply kirchoff's laws to AC circuits, with some restrictions.
The simple idea of resistance is generalised to impedance, so that you can study the behaviour of capacitors and inductors as well as resistors, and the currents and voltages are represented by complex exponentials instead of just sines or cosines, making the mathematics much more straightforward (honestly).
Strictly speaking, kirchoff's voltage law doesn't apply to inductors and you have to use faraday's law, but mostly you will see kirchoff applied to idealised circuit elements.