Question

what is longest wavelength of paschen series of li2+ ion
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Answer 1

Answer:

THE ANSWER TO THIS QUESTION IS 16/(7R) WHERE R IS RYDBERG CONSTANT

Explanation:

In the paschen series the electrons have a transition from various electronic levels to a lower energy level of n=3.

To compute the wave number that is the inverse of wavelength we use the formula

1/λ=RZ^2([1/n1^2]-[1/n2^2])

here n1=3 and n2=4 as the transition between two successive orbits  involves low energy difference thereby huge wavelength from the formula

E=hc/λ

thereby computing

1/λ=R×9[{1/9}-(1/16)]

1/λ=R×7/16

⇒λ=16/7R