An electron in the third energy level of an excited `He^(o+)` ion returns back to the ground state.The photon emitted in the process is absorbed by a stationary hydrogen atom in the ground state. Determine the velocity of the photoelectron ejected from the hydrogen atom in metre per second.

Answer

A, C, D

Explanation

`He^(o+)(Z = 2),n = 3 rarr n = 1`
` overset(Delta E + H atom)underset]((n = 1))]`= emitted find `l//c`
`Delta E = 13.6 (2)^(2)[(1)/(1^(2)) - (1)/(3^(2))] = (13.6 xx 4 xx (8)/(9))`
`Delta E - phi ) = KE = (1)/(2) mV_(e)^(2)`
IE of H atom
`rArr(13.6 xx 4 xx - 13.6 ) = (1)/(2) mV_(e)^(2)`
` rArr ((23)/(9) xx 13.6 ) xx (2)/(9.1 xx 10^(-31)) = V_(e)^(2)`
` rArr V_(e) = sqrt(1.222 xx 10^(13)) = 3.49 xx 10^(6) m s^(-1)`