Final answer:
Mrs. Schacter's behavior upon arrival at a camp is ironic because her predictions, which are dismissed as craziness, turn out to be true.
Step-by-step explanation:
The ironic behavior of Mrs. Schacter upon arrival at a camp can be seen in her predictions of a horrifying future, which turn out to be accurate. She repeatedly warns the other prisoners about the terrible things that await them, such as the crematoriums and the fire. Initially, the other prisoners dismiss her as crazy and delusional, but as they later realize the truth of her predictions, it becomes clear that her behavior was not only ironic, but also a tragic foreshadowing.