Energy of an electron is givem by `E = - 2.178 xx 10^-18 J ((Z^2)/(n^2))`. Wavelength of light required to excited an electron in an hydrogen atom from level `n = 1` to `n = 2` will be
`(h = 6.62 xx 10^-34 Js` and `c = 3.0 xx 10^8 ms^-1`).

Options

A. `6.500xx10^(-7)m`
B. `8.500xx10^(-7)m`
C. `1.214xx10^(-7)m`
D. `2.816xx10^(-7)m`.

Answer

C

Explanation

`DeltaE=(E_(2)-E_(1))`
`h(c)/(lamda)=((-2.178xx10^(-18))/(4))-((-2.178xx10^(-18))/(1))`
`(6.62xx10^(-34)xx3xx10^(8))/(lamda)=2.178xx10^(-18)[1-(1)/(4)]`
`lamda=(6.62xx10^(-34)xx3xx10^(8)xx4)/(3xx2.178xx10^(-18))=1.214xx10^(-7)m`