When a beam of atoms emerges from an oven at the absolute temperature T, the most probable de Broglie wavelength for a given atom is \lambda _{{\rm{mp}}} = \frac{h}{{\sqrt{{5mkT}}}}. In this expression, m is the mass of an atom, and k is Boltzmann's constant.
What is the most probable speed of a hydrogen atom emerging from an oven at 400K.