What is effective atomic number of $$\mathrm{Pt}$$ in $$\left[\mathrm{Pt}\left(\mathrm{NH}_3\right)_4\right]^{2+}$$ ? (Given atomic number of $$\mathrm{Pt}=78$$)

Which of the following complexes is diamagnetic and square planar?

Identify the number of unpaired electrons present and geometry respectively of [Co(NH$$_3$$)$$_6$$]$$^{3+}$$ complex.

Which among the following statements about $$\left[\mathrm{Ni}(\mathrm{CN})_4\right]^{2-}$$ is $$\underline{\text { NOT }}$$ true?