A physical change is a change in which something is changed in appearance. For example, if I cut a piece of paper in half.
A chemical change is when the composition (or the makeup) of something is changed. For example, baking soda and vinegar. They react to form a whole different thing.
Picking up a paper clip with a magnet doesn't change its appearance. It doesn't change its composition. The magnet only picks up the paper clip because it attracts magnetic objects, if you were to take it off of the paper clip it would still be the same paper clip, and most likely look the same.
The answer is (4) CH3CH2OH and CH3OCH3. You need to figure out which pair has the same molecular formula which means that they have the same number of same atoms. Then you can get the write answer.