What knowledge does Ben provide that shows he is clearly “a child of the atomic age”? How does Peyton get injured in this scene?

Question One: From the text:

Ben Franklin, staring to the south, said, "I don't see any mushroom cloud. Don't they always have a mushroom cloud?"

Ben Franklin said, "You're right, Randy. If they laid an egg close, we could get flash burns. Then there's radiation."

Question Two:

Peyton was injured looking at the blast of the mushroom cloud.

Peyton screamed, "I can't see! I can't see, Mommy. Mommy, where are you?" Her eyes were wide, her face tear-stained and mottled. Arms outstretched, she was moving across the porch with tiny, stiff, uncertain steps.