$${p = \sqrt{2mK} \\ = \sqrt{(2)(9,11 \times 10^{-31}\, \mathrm{kg})(120\, \mathrm{eV})(1,60 \times 10^{-19}\, \mathrm{J/eV})} \\ = 5,91 \times 10^{-24}\, \mathrm{kg \cdot m/s}}$$