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 ratio of the kinetic energy of the `n = 2` electron for the H atom to that of `He^(+)`ion is

Options

A. Its potential energy decreases
B. Its kinetic energy increases
C. Its angular momentum remain unchanged
D. Wavelength of de Broglie wave associated with the electron decrease

Answer

A, B, C

Explanation

As electron from higher to orbit `En darr` hence `KREn uarr [KE = En]`
Similarly `Pen darr [Pen = 2En]`
Angular momentum `(L) = nh//2pi` hence `1 darr` as `n darr`
`lambda_(e) = h//mv_(n)[Ken uarr ` hence Vn darr]` therefore `lambda_(n) darr`