2nd excited state implies that n=3.
Now the inner most radius i.e., for n=1, r'= 5.3*10^-11 m
Now we know radius of nth orbit is given by r(n) = r' * n^2
There the radius of the second excited state i.e., r(n =3) = r' * 3^2 = 5.3*10^-11*9 = 4.77*10^-10 m.
I hope my answer helps. Have a great day!
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