The collision of an electron with kinetic energy 5.5 eV and a hydrogen atom in its ground state can be described as

Options

A. completely inelastic
B. may be completely inelastic
C. may be partially elastic
D. elastic

Answer

D

Explanation

Given, kinetic energy of electron `=5.5 eV`.
The energy required to excite a hydrogen atom from ground state `(n=1)` to first excited state `(n=2)` is
`DeltaE=E_(2)-E_(1)`
`=-34-(-13.6)=10.2 eV`
When an electron collides with hydrogen atom in the ground state with energy of 5.5 eV which is less than 10.2 eV, then it will not be able to excite hydorgen atom into first excited state. Therefore, electron will not give any energy to the hydrogen atom. Hence, the total kinetic energy of electron remains conserved. Hence, its collision with hydrogen atom is elastic.