Ionization potential of hydrogen atom is $13.6 \mathrm{eV}$. Hydrogen atoms in the ground state are excited…

Ionization potential of hydrogen atom is $13.6 \mathrm{eV}$. Hydrogen atoms in the ground state are excited by monochromatic radiation of photon energy $12.1 \mathrm{eV}$. According to Bohr's theory, the spectral lines emitted by hydrogen will be:
  1. one
  2. two
  3. three
  4. four

Solution

According to question $\begin{aligned} & 12.1=13.6\left(\frac{1}{l^2}-\frac{1}{n^2}\right) \\ & \Rightarrow \quad n^2=\frac{13.6}{1.5}=9 \\ & \Rightarrow \quad n=3 \\ & \end{aligned}$ Number of spectral lines emitted $\begin{aligned} & =\frac{n(n-1)}{2}=\frac{3 \times 2}{2} \\ & =3 \end{aligned}$

Asked in: NEET 2006

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