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What is the wavelength of light emitted when the electron in a hydrogen atom undergoes a transition from an energy level with n = 4 to an energy level with n = 2? - Chemistry

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प्रश्न

What is the wavelength of light emitted when the electron in a hydrogen atom undergoes a transition from an energy level with n = 4 to an energy level with n = 2?

संख्यात्मक

उत्तर

The ni = 4 to nf = 2 transition will give rise to a spectral line of the Balmer series. The energy involved in the transition is given by the relation,

`"E" = 2.18 xx 10^(-18) [1/"n"_"i"^2 - 1/"n"_"j"^2]`

Substituting the values in the given expression of E:

`"E" = 2.18 xx 10^(-18) [1/4^2 - 1/2^2]`

`= 2.18 xx 10^(18) [(1-4)/16]`

`=2.18xx10^(-18)xx(-3/16)`

E = – (4.0875 × 10–19 J)

The negative sign indicates the energy of emission.

Wavelength of light emitted (`lambda`)  = `("hc")/"E"`

`("since"  "E" = ("hc")/lambda)`

Substituting the values in the given expression of λ:

`lambda  = ((6.626 xx 10^(-34))(3xx10^8))/(4.08875xx10^(-19))`

`lambda = 4.8631 xx 10^(-7) m`

`= 486.3 xx 10^(-9)` m

= 486 nm

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पाठ 2: Structure of Atom - EXERCISES [पृष्ठ ६९]

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एनसीईआरटी Chemistry - Part 1 and 2 [English] Class 11
पाठ 2 Structure of Atom
EXERCISES | Q 2.13 | पृष्ठ ६९
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