Calculate the energy emitted when electrons of `1.0 g`1 of hydrogen transition giving spectrum lines of the lowest in the visible regain of its atomic spectrum
`R_(H) = 1.1 xx 10^(7) m^(-1) , c= 3 xx 10^(8) m s^(-1)` and `h = 6.62 xx 10^(-34) J s`

Explanation

For visible line spectrum, i.e. Balmer series `n_(1) = 2` Also for minimum energy transion `n_(2) = 3` so
`:. (1)/(lambda) = R_(H)((1)/(n_(1)^(2))- (1)/(n_(2)^(2)))`
`therefore1/lambda=R_(H)(1/2^(2)-1/3^(2))`
`= 1.1 xx 10^(7)((1)/(4)-(1)/(9)) = 1.1xx 10^(7) xx (5)/(36)m^(-1)`
`:. lambda = 6.55 xx 10^(-7) m`
`E = (hc)/(lambda)= (6.62 xx 3.0 xx 10^(8))/(6.55 xx 10^(7)) = 3.037 xx 10^(-19) J`
If N elecytron show the transition in `1 g of H` atom , then energy released `= E xx N`
`= 3.03 xx 10^(-19) xx 6.023 xx 10^(23)`
`= 18.29 xx 10^(6) J = 182.5 J`