EDUCATION (CBSE/UGC NET)

Detailed explanation-1: -On earth, hydrogen occurs chiefly in combination with oxygen in water, but it is also present in organic matter such as living plants, petroleum, coal, etc.

Detailed explanation-2: -When molecular hydrogen (H2) and oxygen (O2) are combined and allowed to react together, energy is released and the molecules of hydrogen and oxygen can combine to form either water or hydrogen peroxide. These two processes are represented by the two chemical equations shown at right.

Detailed explanation-3: -Here on earth, vast numbers of hydrogen atoms are contained in water, plants, animals and, of course, humans. But while it’s present in nearly all molecules in living things, it’s very scarce as a gas – less than one part per million by volume.

Detailed explanation-4: -Solution : Hydrogen occurs in the earth’s crust, atmosphere and in volcanic gases, also in the interior of the sun in the free state. In combined state it occurs in organic compounds, plants and animals, in acids and in water.