The energy of 2s=orbitals of H, He and Li follow the order

Options

A. `He lt H lt Li`
B. `Li lt He lt H`
C. `Li gt He gt H`
D. `He gt H gt Li`

Answer

B

Explanation

Since, it is 2s-orbital.
So, principal quantum number (n) = 2
Energy of the electron in atom `E_(n)=(-13.6(Z)^(2)eV)/n^(2)`
`" "n=1, 2, 3`
For hydrogen, `E_(H)(n=1)=(-13.6(1)^(2)ev)/4=-3.40eV`
For helium, `E_(He)(n=2)=(-13.6(2)^(2))/4=13.6eV`
For lithium, `E_(u)(n=3)=(-13.6(3)^(2))/4=-30.6eV`
So, the energy of 2s-orbitals of H, He, and Li is
`Li lt He lt H`.