`H_(2)` acts as an oxidising agent when it reacts with highly electropositive alkali metals. For example
`2Na(s) + H_(2)(g) to underset("Sod. Hydride")(2Na^(+)H^(-))`
Here, Na has been oxidised to `Na^(+)` while `H_(2)` has been reduced to hydride `(H^(-))` ion.