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Question: Answered & Verified by Expert
A gas absorbs a photon of $355 \mathrm{~nm}$ and emits at two wavelengths. If one of the emissions is at $680 \mathrm{~nm}$, the other is at:
ChemistryStructure of AtomJEE MainJEE Main 2011
Options:
  • A
    $325 \mathrm{~nm}$
  • B
    $743 \mathrm{~nm}$
  • C
    $518 \mathrm{~nm}$
  • D
    $1035 \mathrm{~nm}$
Solution:
2899 Upvotes Verified Answer
The correct answer is:
$743 \mathrm{~nm}$
$\frac{1}{\lambda_{\text {absorted }}}=\frac{1}{\lambda_1}+\frac{1}{\lambda_2}$
$\Rightarrow \frac{1}{355}=\frac{1}{680}+\frac{1}{\lambda_2}$
$\Rightarrow \lambda_2=742.8 \cong 743 \mathrm{~nm}$

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