Misc: when do you prune fruit trees??

Questions

History : What was the name of the B-29 used at Hiroshima to drop the bomb?

History : What was the nationality of the prisoners in the "Black hole of Calcutta"?

History : What was the third country to get the "bomb"?

History : What's the resting place of those buried at sea?

History : Which U.S. president said, "The buck stops here"?