Question:hard

The wavelength of the radiation emitted is \(λ_0\) when an electron jumps from the second excited state to the first excited state of hydrogen atom. If the electron jumps from the third excited state to the second orbit of the hydrogen atom, the wavelength of the radiation emitted will be \((20λ_0/x)\). The value of \(x\) is

Show Hint

Use \(\frac1\lambda=R\left(\frac{1}{n_1^2}-\frac{1}{n_2^2}\right)\); second excited state is \(n=3\) and third excited is \(n=4\).
Updated On: Oct 1, 2026
  • \(17\)
  • \(21\)
  • \(27\)
  • \(29\)
Show Solution

The Correct Option is C

Solution and Explanation

Step 1: Plan:
Take the ratio of the two wave numbers directly.

Step 2: Steps:
$\frac{1/\lambda}{1/\lambda_0} = \frac{3R/16}{5R/36} = \frac{3}{16}\times\frac{36}{5} = \frac{27}{20}$. So $\frac{\lambda}{\lambda_0} = \frac{20}{27}$ and $x = 27$.
A common slip is taking the third excited state as $n=3$, which would make the two lines identical.

Final Answer:
The value of $x$ is $27$, option (C). \[ \boxed{27} \]
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