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

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

For the given aqueous reaction,which of the statement$(s)$ is (are) true?
$2KI + 2K_3[Fe(CN)_6] \xrightarrow{H_2SO_4} I_2 + 2K_4[Fe(CN)_6]$
$(A)$ The first reaction is a redox reaction.
$(B)$ White precipitate is $K_2Zn_3[Fe(CN)_6]_2$.
$(C)$ Addition of filtrate to starch solution gives blue colour.
$(D)$ White precipitate is soluble in $NaOH$ solution.

Given below are two statements:
Statement-$I$: Hybridisation, shape, and spin-only magnetic moment of $K_{3}[Co(CO_{3})_{3}]$ are $sp^{3}d^{2}$, octahedral, and $4.9 \ BM$ respectively.
Statement-$II$: Geometry, hybridisation, and spin-only magnetic moment values $(BM)$ of the ions $[Ni(CN)_{4}]^{2-}$, $[MnBr_{4}]^{2-}$, and $[CoF_{6}]^{3-}$ respectively are square planar, tetrahedral, octahedral; $dsp^{2}$, $sp^{3}$, $sp^{3}d^{2}$ and $0, 5.9, 4.9$.

Which of the given statements is incorrect?

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 $g \ mol^{-1}: H=1, N=14, O=16, S=32, Cl=35.5, Ca=40, Ni=59$)