MCQ
An electron instially present in an excited state of $H$ atom is further excited to another energy level by an incident photon. It releases $10$ photons while coming back to ground state out of which $7$ have higher energy than incident photon. The electron was instially present in
  • A
    $1^{st}$ excited state
  • $2^{nd}$ excited state
  • C
    $3^{rd}$ excited state
  • D
    $4^{th}$ excited state

Answer

Correct option: B.
$2^{nd}$ excited state
b
Applying

$\frac{\left(n_2-n_1\right)\left(n_2-n_1+1\right)}{2}=10$

$\frac{\left(n_2-n_1\right)\left(n_2-1+1\right)}{2}=10$

$\frac{n_2\left(n_2-1\right)}{2}=10$

$\because \quad n_2=5 \frac{\left(n_2-n_1\right)\left(n_2-n_1+1\right)}{2}=3$

$\frac{\left(5-n_1\right)\left(5-n_1+1\right)}{2}=3$

$\frac{\left(5-n_1\right)\left(6-n_1\right)}{2}=3$

$n_1=3 \quad\left(2^{n d}\right. \text { excite d state ) }$

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For the reaction $X ( s ) \rightleftharpoons Y ( s )+ Z ( g )$, the plot of $\ln \frac{ p _z}{ p ^\theta}$ versus $\frac{10^4}{T}$ is given below (in solid line), where $p_z$ is the pressure (in bar) of the gas $Z$ at temperature $T$ and $P ^{\ominus}=1$ bar.

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