How fast is an electron moving if it has a wavelength equal to the distance it travels in one second?

With what velocity must an electron travel,so that its momentum is equal to that of a photon of wavelength $663 \ nm$ (in $m/s$)?

The wavelengths of electron waves in two orbits are in the ratio $3: 5$. The ratio of the kinetic energy of the electrons will be:

Similar to electron diffraction, neutron diffraction is also used for the determination of the structure of molecules. If the wavelength used is $800 \, pm$, calculate the characteristic velocity associated with the neutron.

$A$ proton and a $Li^{3+}$ nucleus are accelerated by the same potential. If $\lambda_{Li}$ and $\lambda_{P}$ denote the de Broglie wavelengths of $Li^{3+}$ and proton respectively,then the value of $\frac{\lambda_{Li}}{\lambda_{P}}$ is $x \times 10^{-1}$. The value of $x$ is ............
(Rounded off to the nearest integer)
(Mass of $Li^{3+} = 8.3 \times \text{mass of proton}$)

The de-Broglie wavelength of a particle with mass $1 \, g$ and velocity $100 \, m/sec$ is