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Atoms — Physics STD 12 Science — Question

Gujarat BoardEnglish MediumSTD 12 SciencePhysicsAtoms3 Marks
Question
A positive ion having just one electron ejects it if a photon of wavelength $288\mathring{\text{A}}$ or less is absorbed by it. Identify the ion.
✓

Answer

$\lambda=228\mathring{\text{A}}$
$\text{E}=\frac{\text{hc}}{\lambda}=\frac{6.63\times10^{-34}\times3\times10^{8}}{228\times10^{-10}}=0.0872\times10^{-16}$
The transition takes place form n = 1 to n = 2
Now, ex. $\frac{13.6\times3}{4\times\text{z}^2}=0.0872\times10^{-16}$
$\Rightarrow\text{z}^2=\frac{0.0872\times10^{-16}}{13.6\times3\times1.6\times10^{-19}=5.3}$
$\Rightarrow\text{z}=\sqrt{5.3}=2.3$
The ion may be Helium.

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