Why don't people understand that there is no nominal nuclear explosive? Yields vary from under 1KTon to 50MTon! Also the answer to your question depends on:
No single numeric answer can be given.
It is difficult to determine an exact number of nuclear warheads needed to end all life on Earth as it would depend on various factors such as targeting and the size of the warheads. However, it is believed that even a small fraction of the world's nuclear arsenal could potentially cause catastrophic global consequences.
more than has ever been built.
There hasn't been a test on that yet, it would also depend on how big the warheads carried were.
A supernova releases an immense amount of energy, equivalent to billions of nuclear warheads exploding concurrently. The exact number would depend on the yield of each warhead, but it would be a vast number.
If the North Koreans would start a nuclear war the earth would be pretty much torn up and polluted. The North Koreans' primary weapons are the nuclear warheads, so they spend millions of research money on it. The results would be devestating if used on the U.S as its current state is no good. The U.S would crumble.
The US nuclear weapons arsenal is powerful enough to destroy the Earth multiple times over. The exact number of times would depend on the specific yield of each warhead and the total number of warheads available.
If provoked again due to a pre-emptive attack on our homeland, the USA would inot hesitate to use nuclear warheads on another country.
Anywhere between 75 and 200 nuclear weapons.I have read an upper estimate of 400. I would be surprised if it were much less than this, unless some are stored partially dismantled.
These days, depending on the size triggered, just one. One would be sufficient enough to cause a nuclear fallout in witch we will all be in a world of hurt.
It depends completely on how large the asteroid is, how far away it is, and how effectively you want it destroyed (vaporised, knocked off course or broken into manageable chunks).
11 reactors at present, but see the link below
It is difficult to provide an exact number, but experts estimate that as few as 300 nuclear warheads detonated in key cities could result in worldwide devastation, as the resulting nuclear winter would lead to widespread famine and loss of life. Efforts to reduce nuclear stockpiles and promote disarmament are crucial to prevent such a catastrophic scenario.