Question

According to the Bohr model, the energy levels of hydrogen atom can be found by making two assumptions.
(i). The electrons move in circulr orbit and (ii) the angular momentum of the electron in the `n^(th)` energy level is quantized to have a value `n(h)/(2pi)`. The levels calculated with nuclear charge Ze, with a single electron in the orbit, are called Hydrogenic levels. Assume that the two electrons in the ground state of a helium atom occupy the corresponding lowest Hydrogenic level.
Q. The minimum repulsive energy between the two electrons would then be:
A. 3.4 eV
B. 6.8 eV
C. 13.6 eV
D. 27.2 eV

Answer 1

Correct Answer - D
For singly ionised He atom, ground state energy is
`((-Ze^(2))/(2r))=-54.4eV`
`(-2e^(2))/(2r)=-54.4eV`
`(e^(2))/(2r)=27.2eV`
`therefore` Minimum repulsive energy =27.2eV
(Two electrons will lie diametrically opposite).