WHAT is the condensed hydrogen and how they use it in nuclear bomb?

Answer 1

Hydrogen comes in three isotopic forms: normal hydrogen, no neutrons, deuterium, one neutron, and tritium, two neutrons. Deuterium and tritium are the components of a hydrogen bomb, called a thermonuclear device. They combine to make helium (two protons, two neutrons), one rogue neutron, and a tremendous amount of energy. This is the same nuclear reaction which keeps the sun going.

Incidentally, deuterium oxide, chemically and almost physically identical to water (but physically heavier), is called "heavy water", and is used to modulate the reaction in nuclear power reactors.

Answer 2

Condensed (liquid) hydrogen is not used in modern nuclear weapons. They use Lithium 6 Deuteride. Li 6 tranmutes into Tritium T upon neutron bombardment by the fission primary. The fusion reaction, then, is with the D and the T nuclei.

Answer 3

tritium was responsible for accidental irradiations of several scientists due to unexpected test results..

It is considered an assisted multiplier of the primary reaction.