Viruses can multiply very quickly, and so they can go through natural selection at a much quicker rate, allowing certain vaccine resistant mutations to take over a population.
The layer of the sun is in three equally side the sun the moon and the galaxy
Technically, the black widow spider is the deadliest spider despite it's size, due to it's overwhelmingly potent venom, which can and will kill a human if no medical attention is sought out for the person bit.
Condensation, because when water vapor turns into water again it needs to release energy to do so. Its like turning ice into water again.
I hope this helped ^_^