Which of the following system in an octahedral complex has maximum unpaired electrons?

The correct IUPAC name of cis-platin is

Crystal field splitting energy (CFSE) for $$\left[\mathrm{CoCl}_6\right]^{4-}$$ is $$18000 \mathrm{~cm}^{-1}$$. The crystal field splitting energy (CFSE) for $$\left[\mathrm{CoCl}_4\right]^{2-}$$ will be

The complex hexamineplatinum(IV)chloride will give _____ number of ions on ionisation.