Calculate the energy emitted when electrons of `1.0 g` of hydrogen undergo transition giving spectrum lines of the lowest energy in the visible region 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`

Answer

A, B, C

Explanation

For H atom ,the wspectrum lines in visible region corresponding to Balmer lines of `n_(2) = 2` Now, for lower energy photon, the required transition will be from `3 rarr 2` Using the relation for `Delta E`
`Delta E = 2.178 xx 10^(-18) (1)^(2)((1)/(2^(2)) - (1)/(3^(2))) (1)/("atom")`
Now the `2.0 g `atom , the energy relation will be
`E = (2 xx 6.023 xx 10^(23)) xx 2.18 xx 10^(-18) ((5)/(36)) J`
`= 3.63 xx 10^(5) J = 3.63 xx 10^(12) erg`