For what kinetic energy of a neutron will associated de-Broglie

(i) For what kinetic energy of a neutron will associated de-Broglie wavelength be 1.40 x ${{10}^{-1}}$ m?
(ii) Also find the de-Broglie wavelength of a neutron, in thermal equilibrium with matter, having an average kinetic energy of (3/2) kT and temperature is 300 K.