The north magnetic pole of a compass magnet points towards earth's geographic and earth's magnetic

The north magnetic pole of a compass magnet points towards earth's geographic NORTH and earth's magnetic SOUTH.  

Explanation:

Like poles repel each other and unlike poles attract each other. A magnetic compass is based on this property of magnets. It has magnetic needle and it is known that every magnet has two poles - North pole and south pole. A compass is used find the directions. The needle points towards North. This north is actually the Earth's geographic north and would be magnetic south because south pole will attract north pole of the compass.

we need to know the time interval during which the force acts. impulse of force = momentum change

the answer is the first electromagnet (a). this is because it has more coils around the ferromagnetic material. increasing the number of coils increases the surface area in which the metal interacts with the current in the coil. this enables more atoms in the metal to become aligned hence becoming more magnetized.