Heat from impact, and radiation poisioning and radioactive contamination.
yes
yes. enough to kill everybody on earth several times
At this time the US builds no nuclear bombs. A small number of existing bombs are refurbished as needed.
nuke it with fifty nuclear bombs
Conventional.
None, the US currently only refurbishes existing bombs.
Sort of - The US has nuclear arms and Puerto Rico is a US territory.
Because its a nuclear bomb, it can kill millions of people in a matter of minutes.
It is difficult to determine the exact number of nuclear bombs it would take to kill everyone in the world, as many factors such as location and size of the bombs would come into play. However, it is estimated that a few hundred strategically placed nuclear bombs could have catastrophic global consequences.
Nuclear, plane, land, and sea bombs.
the US
At this time Russia.