Which of the following are paramagnetic?

A. $\left[\mathrm{NiCl}_4\right]^{2-}$

B. $\mathrm{Ni}(\mathrm{CO})_4$

C. $\left[\mathrm{Ni}(\mathrm{CN})_4\right]^{2-}$

D. $\left[\mathrm{Ni}\left(\mathrm{H}_2 \mathrm{O}\right)_6\right]^{2+}$

E. $\mathrm{Ni}\left(\mathrm{PPh}_3\right)_4$

Choose the correct answer from the options given below :

The correct order of the wavelength of light absorbed by the following complexes is,

A. $\left[\mathrm{Co}\left(\mathrm{NH}_3\right)_6\right]^{3+}$

B. $\left[\mathrm{Co}(\mathrm{CN})_6\right]^{3-}$

C. $\left[\mathrm{Cu}\left(\mathrm{H}_2 \mathrm{O}\right)_4\right]^{2+}$

D. $\left[\mathrm{Ti}\left(\mathrm{H}_2 \mathrm{O}\right)_6\right]^{3+}$

Choose the correct answer from the options given below:

Ethylene diaminetetraacetate ion is a/an:

Which of the following is not an ambidentate ligand?