What are the answers to the riddles?
To avoid spoilers. As Prix mentioned, there are no definitive answers to the riddles. The answers that Haru and Tokaku come up with are simply "their own answers." The riddles are presented to Tokaku in situations where she fills in the Riddles with answers that have been decided based on her current situation and mental state.

1. What is the World Full of? (Haru answers" forgiveness")
11. Therefore, the World is Full of ______?


One might answer "lies" for the second, while Haru answers "forgiveness" for the first. However both Haru and Tokaku's situation and mental state are drastically different. 1. being a sort of happy/mellow situation with her class mates, 11. being dramatic and sad due to the prior events.