What creates HYDROGEN , HELIUM , NITROGEN that's creates AIR in turn creates WATER ?

Question

HANGFIRE : quite good answer.

Answer 1

Hydrogen and Helium were created by the Big Bang.  Some Helium and all Nitrogen was created in stars and released into the universe when the biggest stars exploded as supernovas.  Also Oxygen, which you somehow forgot to mention.

All of these elements were in the gas cloud that formed our solar system.  The earth is too light to hold onto hydrogen and helium, but every other natural element is present in the earth.  Water formed as a result of natural chemical processes.

Answer 2

Hydrogen and helium were perhaps produced within the first few thousands of a seconds after the big band. The larger molecules, nitrogen, oxygen, etc were produced inside of stars by fusion. The heavier elements were all created in explosions of stars. The Hydrogen bonds with oxygen under certain conditions, creating water. This equilibrium defines many analytical techniques, such as pH. In Water, the Hydrogen and Oxygen equally break apart and dissolve as seperate molecules, on the order of 1X10^-7 Moles per liter.