the wavelength of light that must be absorbed to excite a hydrogen electron from level `n = 1` to level `n = 2`, will be
`(n = 6.625 xx 10^(-34) Js, C = 3 xx 10^8 ms^(-1))`

Options

A. `1.325 xx 10^(-10) m`
B. `1.325 xx 10^(-7) m`
C. `5.300 xx 10^(-10) m`
D. `2.650 xx 10^(-7)m`

Answer

B

Explanation

`DeltaE=-2xx10^(-18)J[1/2^2-1/1^2]`
`=-2xx(-3/4)xx10^(-18)J`
`=1.5xx10^(-18)J`
`DeltaE =(hc)/lambda`
`lambda=(hc)/(DeltaE) =(6.625xx10^(-34)xx3xx10^8)/(1.5xx10^(-18))`
`=(19.875xx10^(-26))/(1.5xx10^(-18))`
`=1.325xx10^(-7)m`