Hello candidate,

This given question its mentioned that an electron is in the second excited States which makes the principal quantum Number equal to 3 and has to get the excited to the ground state which makes the second principal quantum number equal to 1 between which the transition is to take place.

The formula for De broglie's wavelength is given by 1/wavelength= R*(1-1/9), where the R can be referred as Rydberg's constant. So, the value of lambda in terms of rydberg constant is equal to 9/8R.

Hope you found it helpful.

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