Question

State any two postulate of bohr's theory of hydrogen atom what is the maximum possible number of spectral lines observed when the hydrogen atom is in its second excited state justify your answer

Answer 1

Bohr postulates

(1) the electrostatic force between nucleus and electron provides it necessary centripetal force i.e., mv²/r= 1/4π€. × Ze.e/r²

(2) electrons revolve in those orbits only in which their angular momentum is integral multiple of h/2π ie mvr=nh/2π

(3) when electron goes from higher orbit to lower orbit, there is emission of energy but when it goes from lower to higher orbit, energy is absorbed in terms of photon (hv) ie E2-E1=hv

Number of lines produced when electron from nth shell drops to ground state = n(n-1)/2

n = 3 for 2nd exited state

so no. of lines= 3(3-1)/2 = 3

3—-> 2 —→ 1

3—-> 2

2 —-> 1

so three spectral lines possible :)