What is the geometry of the $[Ni(CO)_4]$ complex?

When $Ag^{+}$ reacts with excess of sodium thiosulphate,the obtained species having charge and geometry respectively will be?

Which of the following metal carbonyl complexes is correctly matched with its magnetic property and geometry?

On the basis of valence bond theory,discuss the geometrical shapes and magnetic properties of the following $4$-coordinated complexes:
$(i)$ $[NiCl_{4}]^{2-}$
$(ii)$ $[Ni(CN)_{4}]^{2-}$
$(iii)$ $[Ni(CO)_{4}]$
$(iv)$ $MnO_{4}^{-}$

Which of the following statements is correct?

Which of the following complexes has $dsp^2$ hybridisation?