Hurrah, we come to the end of the module! We started by asking if paper can be put inside a microwave oven. The answer is: it depends! If the paper is a little wet, the microwave oven will heat the water molecules. If the heat increases the temperature to above paper's ignition temperature, the paper may catch fire!
Also, if the paper is recycled, it may have some very tiny metal pieces in it. If the metal parts create sparks, the paper may again catch fire.
So, usually, paper is microwave-safe, especially if there is food in the microwave. But, it is may not be safe to microwave only paper.