When the electron of an excited Hydrogen atom jumps from n = 3 to the ground state, the recoil velocity of the Hydrogen atom is…. (Mass of proton = 1.67 x 10-27 kg)

E = Energy of emitted proton 13.61-132 eV=12.08 eVMomentum of emitted photon, p=Ec=12.08 x 1.6 x 10-193 x 108 kg-m/sRecoil velocity pm=12.08 x 1.6 x 10-193 x 108 x 1.67 x 10-27 m/s=3.85 m/s