Ionisation energy of `He^(+) " is " 19.6 xx 10^(-18)J "atom"^(-1)`. The energy of the first stationary state `(n = 1)` of `Li^(2+)` is

Options

A. `4.41 xx 10 ^(-19) J "atom"^(-1)`
B. `-4.41 xx 10 ^(-17) J "atom"^(-1)`
C. `-2.2 xx 10 ^(-15) J "atom"^(-1)`
D. `8.82 xx 10 ^(hatu17) J "atom"^(-1)`

Answer

2

Explanation

I.P of `He^(+)= 19.6 xx 10^(-8)J//atom`
`(E_(1))_(He^(+)) = - 19.6 xx 10^(-18)`
`(E_(1))_(He^(+))/((E_(2))_(Li^(+2)))=((Z_(1)^(2)))/((Z_(2))_(Li^(+2))^(2)) xx `
`-(19.6xx10^(-18))/((E_(1))_(Li^(+2)))=((2)^(2))/((3)^(2))=((1)^(2))/((1)^(2))`
`((n_(2))_(Li^(+2))^(2))/((n_(1))_(He^(+))^(2))`
`(E_(1))_(Li^(+2)) = (9)/(4) xx (-19xx10^(-18))`
`=- 4.41 xx 10^(-17)J//"atom"`