What makes a competitive industry likely to evolve toward monopoly?

Well no matter how competitive a company is there is always going to be times when they don't have a lot of work to do, those are the times when the employees might pull out board games, it's not always going to be monopoly, they could play clue or life or anything else...

All joking aside, all the questions you posted sound like a questions right out of an economics textbook and we don't answer homework problems for you here on this site, this is why no ones has replied. If you show you know the subject matter but don't see the answer someone might be able to suggest an answer. Have you tried reading wikipedia articles about competitive industries and monopolies already? Or your text book?