Which of the following species will produce the shortest wavelength for the transition `n = 2 "to" n= 1` ?

In which of the following N-N bond length is shortest?

Which of the following has the shortest N-N bond length ?

Which transition in the hydrogen atomic spectrum will have the same wavelength as the transition n=4 to n=2 of he^+ spectrum?

Which of the following transitions produce the longest wavelength photon (as shown in the following figure)?

The ratio of the wavelength for the transition from n = 2 to n = 1 in Li^(++).He^(+) and H is

Which transition in the hydrogen spectrum have the same wavelength as Balmer transition, n = 4 to n = 2 , of H2^+ spectrum ?