Question

The recoil speed of hydrogen atom after it emits a photon in going from n=5 state to n=1 state is 1) 1 5.718ms 2) 1 8.418ms 3) 1 4.178ms 4) 1

Answer 1

Explanation:

E = 13.6/n²

  = 13.6 ev x 24/25

   =  20.8 x 10^-19 J

As the emitted article is photon E= P c

E/c = mv --------- > v = E/mc

v =  20.8 x 10^-19 J / 1.6 x 10^-27 x 3 x 10^8

  = 4.178 m/s