By a nuclear fusion reaction: H + H + 2n ==>> He Yes, this is true. I want, here, to put it into a better picture for common folk. This Bang is similar to the nuclear furnace that is out Sun....
Short answer: Yes. Technically correct answer: Depends on the water. Hydrogen is an element defined by having 1 proton. However elements can have different numbers of neutrons and still be the same...
A piece of dust is exactly half way between the size of the Earth and an atom.
Atoms are pretty darn small. Their outer boundaries are set up by moving electrons, so they aren't well defined....