In what does the reaction of hexene and dihydrogen result?

$\text{3-hexene + dihydrogen "rarr" hexane}$
${\text{H"_3"CCH"_2"CH=CHCH"_2"CH"_3 + "H"_2 rarr"H"_3"C(CH"_2)_4"CH}}_{3}$
The addition of dihydrogen is clear if we consider the molecular formulae of product of reactant, i.e. ${\text{C"_6"H}}_{14}$, the alkane product, versus ${\text{C"_6"H}}_{12}$, the olefin reactant; clearly dihydrogen must be added.