Question

If E₁, E₂, E₃ are the respective kinetic energies of an electron an alpha particle and a proton each having the same Debroglie’s wavelength then

Answer 1

If we write de Broglie equation and try to get the kinetic energy in terms of wavelength and h, you will see that K.E. is a inverse Proportional func. of mass. Alpha particle is heaviest 4 a.m.u. So its K.E will be least, then comes proton 1 a.m.u and highest will be of an electron whose mass is least.  

So E₁>E₃>E₂