2. Which of the following sentences is correct? A magnet has a positive pole and a negative pole. Opposite poles attract and like poles repel. An object whose particles are pointing in different directions has a ferromagnetic effect. An object that does not respond naturally to magnets whose molecules are grouped in pairs and cancel each other out has a diamagnetic effect.

The correct sentence is: "Opposite poles attract and like poles repel."<br /><br />Explanation:<br />- A magnet has a north pole and a south pole, not a positive and negative pole.<br />- Opposite poles (north and south) attract each other, while like poles (north and north or south and south) repel each other.<br />- The ferromagnetic effect refers to the phenomenon where certain materials, such as iron, become strongly magnetized in the presence of a magnetic field. This is not related to the direction of particles.<br />- Diamagnetic materials are those that do not respond naturally to magnets and are slightly repelled by a magnetic field. This is not related to molecules being grouped in pairs and canceling each other out.