Consider atoms `H, He^(+), Li^(++)` in their ground states. Suppose `E_(1), E_(2)` and `E_(3)` are minimum energies required so that the atoms `H He^(+), Li^(++)` can achieve their first excited states respectively, then

Options

A. `E_(1)=E_(2)=E_(3)`
B. `E_(1) gt E_(2) gt E_(3)`
C. `E_(1) lt E_(2) lt E_(3)`
D. `E_(1) = E_(2) E_(3)`

Answer

C

Explanation

`Delta E prop Z^(2)`
i.e. greatest for `Li^(++)` and minimum for H.