Which of the following elements is not a transition element?

What is the condensed electron configuration of ${\mathrm{Co}}^{2+}$?

 What is the condensed electron configuration of ${\mathrm{Fe}}^{2+}$?

What is the ligand in the complex ${\left[{\mathrm{NH}}_4\right]}_2\left[\mathrm{Fe}{\left({\mathrm{H}}_2\mathrm{O}\right)}_6\right]{\left[{\mathrm{SO}}_4\right]}_2$?

What is the oxidation state of iron in the complex $\mathrm{Na}\left[\mathrm{Fe}\right(\mathrm{EDTA}\left)\right].3{\mathrm{H}}_2\mathrm{O}$?

What is the total charge, $\mathrm{n}$, in the following complex of $\mathrm{Ni}\left(\mathrm{II}\right), [\mathrm{Ni}{\left({\mathrm{NH}}_3\right)}_6{]}^{\mathrm{n}}$?

What of the following can act as a ligand?

I. ${\mathrm{PH}}_3$

II. ${\mathrm{H}}_2\mathrm{O}$

III. ${\mathrm{NO}}_2^{-}$

Which electron transitions are responsible for the colours of transition metal compounds?

Which salts form coloured solutions when dissolved in water?

I. ${\mathrm{ZnCl}}_2$

II. ${\mathrm{FeBr}}_2$

III. $\mathrm{Co}{\left({\mathrm{NO}}_3\right)}_3$