The speed of a proton is $c / 20$. What will be the de Broglie wavelength associated with it?

An $\alpha$-particle,a proton,and an electron have the same kinetic energy. Which one of the following is correct in the case of their De-Broglie wavelength?

The work done to accelerate an electron from rest so that it can have a de Broglie wavelength of $6600 \text{ Å}$ is nearly (Planck's constant $= 6.6 \times 10^{-34} \text{ J s}$ and mass of electron $= 9 \times 10^{-31} \text{ kg}$)

If the de Broglie wavelengths of an electron and a proton are equal,then the kinetic energy of the electron is ........

An electron microscope uses electrons of $40 \ keV$. The de Broglie wavelength associated with these electrons is approximately:

An $\alpha$ particle and a carbon $12$ atom have the same kinetic energy $K$. The ratio of their de-Broglie wavelengths $(\lambda_{\alpha} : \lambda_{C12})$ is