Q.1
Bomb dropped on Hiroshima at 8:15 A.M. on August 6, 1945, near the end of World War II.

Q.2
Definition of "critical mass"

Q.3
TNT - a measure of explosive yield

Q.4
Contains 0.7 % uranium-235, 99.3 % uranium-238, and a trace of uranium-234

Q.5
An atomic nucleus and one or more neutrons collide and merge to form a heavier nucleus

Q.6
A neutron collides with U-235 and bounces off

Q.7
Definition of "implosion"

Q.8
Definition of to "fly off"