In a mixture of `H - He^(+) gas (He^(+)` is singly ionized He atom), H atom and `He^(+)`ion are excited to their repectve first excite states. Subsequently , H atoms transfer their total excitation energy to `He^(+)`ion (by collisitions). Assume that the Bohr model of atom is exctly valid.
`n = 4 overset( H atom)___ 0.85 eV overset (He^(+) atom)_ - 3.4 eV`
`n = 3 to - 1.51 eV_ to - 6.04 eV`
`n = 2 to - 3.4 eV to - 13.6 eV`
`n = 1 to - 13.6 eV _to -= 54.4 eV`
The quamtum number `n` of the state finally populated in `He^(+)` ions in

Options

A. 1
B. 2
C. 4
D. 6

Answer

C

Explanation

In `H_(1 rarr 2)` the excitation transfer their excitation energy `(10.2 eV)` to the electron in `He^(o+)`is further excited to say `n = n_(2)` thus` 10.2 = 13.6 xx 2^(2) xx (1//2^(2) - 1//n_(2)^(2))` therefore `n_(1) = 4`