One mole of `He^(o+)` ions is excited .An anaylsis showed that `50%` of ions are in the third energy level `25%` are in the second energy level and the remalining ary in the first energy level .Calculate the energy emitted in kilojoules when all the ions return to the ground state

Explanation

`Delta E = 2.176 xx 10^(-18)Z^(2)[(1)/(1^(2)) - (1)/(n^(2))]1 "per atom" `
Energy released when electron falls to `n = 1 is = {50%[2.176 xx 10^(-18) xx 4(1 - (1)/(9))]`
`+ 25%[2.176 xx 10^(-18) xx 4(1 - (1)/(4))]} xx 6 xx 10^(23) xx 10^(-3)(kJ mol^(-1))`