For what kinetic energy of a neutron will the associated de-Broglie wavelength be `1.40 xx 10^-10m`?

What is the de Broglie wavelength

The wavelength of light from the spectral emission line of sodium is 589 nm. Find the kinetic energy at which a neutron, would have the same de-Broglie wavelength.

The kinetic energy of an electrons is equal to the energy of photons. Show that de-Broglie wavelength of this electrons is less than the wavelength associated with a photon.

The wavelength of light the spectral emission line of sodium is 589 nm. Find the kinetic energy at which (a) an electron and (b) a neutron,would have the same de Broglie wavelength.

A nucleus at rest undergoes a decay emitting an alpha -particle of de-broglie wavelength lambda = 5.76 xx 10^(-15) m . The mass of daughter nucleus is 223.40 amu and that of alpha-particle is 4.002 a.m.u.detrmine the total kinetic energy in the final state.Hence,obtain teh mass of the parent nucleus in a.m.u. Given that 1 a.m.u.=931.470 MeV .