Which of the following transition is associated with coloured spectral line

Which of the following transition metal ion is not coloured?

Assume that helium obeys the Bohr theory exactly. Which of the following transition in helium will not give rise to a spectral line which has the same wavelength as some spectral line in the hydrogen spectrum?

Which of the following transition in He^(+) ion will give rise to a spectral line which has the same wavelength as some spectral line in the hydrogen atom ?

Which of the following transition in He^(+) ion will give rise to a spectral line which has the same wavelength as some spectral line in the hydrogen atom ?

Which of the following spectral series in hydrogen atom give spectral line of 4860 Å

Which of the following spectral series in hydrogen atom give spectral line of 4860 overset@A ?

Transition metals normally have unfilled 'd' orbitals which are degenerate. The colour of transition metal ions is due to absorption of light in visible region. Which of the following transition is responsible for providing the colour?

In which of the following transition metal ion complexes, the colour in not due to d-d transition?