MCQ
The frequency of first line of paschen series in spectrum of $Be^{+3}$ ion is
- ✓$\frac{{7RC}}{9}$
- B$\frac{{7RC}}{144}$
- C$\frac{{9RC}}{25}$
- D$\frac{{20RC}}{9}$
✓
Answer
Correct option: A.
$\frac{{7RC}}{9}$
a
$v=\operatorname{RCZ}^{2}\left(\frac{1}{n_{1}^{2}}-\frac{1}{n_{2}^{2}}\right)$
$v=\operatorname{RCZ}^{2}\left(\frac{1}{n_{1}^{2}}-\frac{1}{n_{2}^{2}}\right)$
Here $\quad \mathrm{n}_{1}=3, \mathrm{n}_{2}=4$
$v=\operatorname{RC} \times 16\left(\frac{1}{9}-\frac{1}{16}\right)=16 \mathrm{RC} \times \frac{7}{144}$
$=\frac{7 \mathrm{RC}}{9}$
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