Oxidation state of Cr in [Cr(NH₃)₄Cl₂]⁺.

Let it be x, 1× x+ 4 × 0 + 2 × (–1) = 1 Therefore x=3.

In [Co(NH₃)₃Cl₃],all chlorine atoms are inside the co-ordination sphere so they will not ionise and this com-pound will not give precipitate with AgNO₃.

Let the O. No. of Ni in K₄[Ni(CN)₄] be = x then

4 (+1) + x + (–1) × 4 =0 ⇒ 4 + x– 4 = 0

x = 0

IUPAC name of sodium nitroprusside Na₂[Fe(CN)₅NO]is sodium pentacyanonitrosylferrate (III) because in it NO is neutral ligand. Hence

2 × O.N. of Na + O.N. of Fe + 5×O.N. of CN

1 × O.N. of NO = 0

2 × (+1) + O.N. of Fe +5 ×(–1) + 1 × 0 = 0

O.N. of Fe = 5 – 2 = +3, Hence ferrate (III)

Chlorodiaquatriamminecobalt (III) chloride is [CoCl(NH₃)₃(H₂O₂)]Cl₂

Both are tetrahedral. CO is a strong ligand and P(Ph₃)is a weak ligend.So, CO pair up electrons while P(PH₃)do not pair up. Oxidation state of Ni is zero in carboxyl compound which in other Ni has + 2 oxidation state.

Shape is tetrahedral.

Sodium ethoxide is not an organometallic compound as in this compound carbon is not directly attached withmetal.

[CuCl₂{(O = C(NH₂)₂}₂]

IUPAC name is Potassium trioxalatoaluminate (III).

CN^– is a strong ligand so it forces the electrons to pairup.

In Sc³⁺, no electron is there in d orbital, in Cr³⁺ one electron is unpaired. In Fe³⁺ also one electron is unpaired, Co³⁺ has no unpaired electrons. As both Cr³⁺ and Fe³⁺ contain one electron in unpaired state so both may be paramagnetic. But as we know Fe has moremagnetic properly. Fe³⁺ will be more paramagnetic. Sooption (c) is correct.