1.) Part to a whole
The rest of the questions were hard to read
I believe its literary not completely sure sorryy
Plethora would be the collective noun because it is a group.
If you attached the excerpt, it would be easier to answer your question. Anyway I'll try to guess by giving it few lines in which was mentioned about Ravi who was forgotten. One of the most obvious it the line "They had quite forgotten him.". But the strongest one is this: <span>"Could he hear the children’s voices? It seemed to him that he could. It seemed to him that he could hear them chanting, singing, laughing. But what about the game? What had happened? Could it be over? How could it when he was still not found?"
I hope it will help.</span>