Question

You have been given a bar magnet &asked to mark its North &South poles . How would you do that?

Answer 1

We will bring the north pole of another bar magnet. The side to which it will get attracted to the north pole, we be the south pole and other one will be north pole

Answer 2

We tie a thin and strong thread  to the center of the bar magnet and then hang that vertically from a height.  It rotates freely in horizontal (nearly) and the south pole of the magnetic will point to the North pole of Earth.

North Pole of Magnet will point towards South pole of Earth.