It's not explosive, it's reactive because there is only one electron in the valence shell.
Yes, when hydrogen explodes it produces water.
No Hydrogen is highly unstable and reactive. This is because its valency is 1 e- i.e. it will gain an electron to fulfill its duplet(it is that state when the outermost orbit has 2 e-). Deuterium is...
Yes. It's single free electron is ready to bond to anything.
Light isotopes, like deuterium, tritium, or lithium, or some combination. Deuterium and tritium are hydrogen isotopes, hence the name.