Which among the following cations will not form coloured compounds? (Atomic number $$\mathrm{Cu}=29, \mathrm{Ti}=22, \mathrm{~V}=23, \mathrm{Mn}=25$$)

Which element from following in +3 oxidation state forms colourless compounds?

What is value of spin only magnetic moment of $$\mathrm{Ni}(\mathrm{Z}=28)$$ in +2 oxidation state?

Which of the following elements in their respective oxidation states does not develop spin only magnetic moment? [$$\mathrm{Ti}(\mathrm{Z}=22), \mathrm{Zn}(\mathrm{Z}=30), \mathrm{V}(\mathrm{Z}=23), \mathrm{Cu}(\mathrm{Z}=29)$$]