$[Ni(CO)_4]$ is diamagnetic. Which of the following statements is correct for this complex?

Write down the $IUPAC$ name for each of the following complexes and indicate the oxidation state,electronic configuration,and coordination number. Also,give the stereochemistry and magnetic moment of the complex:
$(i)$ $K[Cr(H_2O)_2(C_2O_4)_2] \cdot 3H_2O$
$(ii)$ $[Co(NH_3)_5Cl]Cl_2$
$(iii)$ $CrCl_3(py)_3$
$(iv)$ $Cs[FeCl_4]$
$(v)$ $K_4[Mn(CN)_6]$

The magnetic moment (spin only) of an octahedral complex having $CFSE = -0.8 \Delta_0$ and surrounded by weak field ligands can be:

Which of the following compounds is not colored yellow?

The ammonia prepared by treating ammonium sulphate with calcium hydroxide is completely used by $NiCl_2 \cdot 6H_2O$ to form a stable coordination compound. Assume that both the reactions are $100 \%$ complete. If $1584 \ g$ of ammonium sulphate and $952 \ g$ of $NiCl_2 \cdot 6H_2O$ are used in the preparation,the combined weight (in grams) of gypsum and the nickel-ammonia coordination compound thus produced is $\qquad$ (Atomic weights in $g \ mol^{-1}: H=1, N=14, O=16, S=32, Cl=35.5, Ca=40, Ni=59$)

Identify the geometrical isomers of the following complexes: