Dihydrogen is less reducing in nature than compared to atomic hydrogen because
Dihydrogen has unpaired electrons.
Dihydrogen is unstable and hence very less reducing.
Dihydrogen has a complete duplet.
The electrons in dihydrogen are in a higher energy state.
Dihydrogen (H2) is less reducing than atomic hydrogen (H) because it is a stable molecule. Atomic hydrogen is a highly reactive species because it has an unpaired electron in its valence shell, making it very eager to react and donate this electron.
However, in the dihydrogen molecule, the two hydrogen atoms are bonded together by a covalent bond, resulting in a stable configuration with no unpaired electrons.