2.

Why does hydrogen occur in a diatomic form rather than in a monoatomic form under normal conditions?

A molecule of hydrogen is formed by the combination of two atoms of hydrogen with one electron each present in the 1s orbital. hydrogen (1s¹) has one electron less than the stable inert gas configuration (He;1s²) and therefore it shares its single electron with an electron of another hydrogen atom to form a stable diatomic molecule. Thus two electrons are present in the hydrogen molecule and both will be accommodated in the molecular orbital of lowest energy. The bond order of H₂ is +1. The positive value of bond order indicates that the H₂ (diatomic) molecules are stable.