JEE Main 2019PhysicsAtomic PhysicsMediumMCQ

JEE Main 2019 — Atomic Physics Question with Solution

JEE Main 2019 (10 Apr Shift 2)

Question

In Li++,electron in first Bohr orbit is excited to a level by a radiation of wavelength λ.When the ion gets de excited to the ground state in all possible ways (including intermediate emissions), a total of six spectral lines are observed. What is the value of  λ ?

(Given:  h=6.63×10-34 J s ;c=3×108 m s-1 )

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Show full solutionCorrect option: A
Correct answer
A10.8 nm

Step-by-step explanation

Total Number of possible spectral lines that can be emmited when atom de-excites from state n to groundstate is C2n
∴ nC2=6⇒n(n-1)2=6⇒n=4
1λ=R z2112-142=1.097×107×9×1-116
⇒λ=10.8 nm

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About this question

This is a previous-year question from JEE Main 2019, covering the Atomic Physics chapter of Physics. PrepSharp catalogues every PYQ from JEE Main with a verified answer key and step-by-step solution prepared by IIT alumni — so you can search by chapter, topic or year and revise efficiently.