∙ Electronegativity is the ability of an atom to attract the shared pair of electrons in a molecule.
∙ When atoms of elements with different electronegativities form a molecule, the atom with higher electronegativity attracts the shared pair of electrons towards itself as a result developing partial charges. These bonds are called polar covalent bond.
∙ The combining elements of hydrogen molecules are identical, i.e. they have no difference in their electronegativity.
Therefore, the bond formed is non-polar covalent bond.