An aqueous pink solution of cobalt (II) chloride changes to deep blue on addition of excess of HCl. This is because____________.

A: [Co(H₂O)]²⁺ is transformed into [CoCl₆]^4- 

B: [Co(H₂O)₆]²⁺ is transformed into [CoCl₄]^2- 

C: Tetrahedral complexes have smaller crystal field splitting than octahedral complexes. 

D: Tetrahedral complexes have larger crystal field splitting than octahedral complex.

CoCl₃.NH₃ + AgNO₃ $\stackrel{}{\to }AgC\mathcal{l}\downarrow \left(2mol\right)$  

$\left[Co{\left(N{H}_3\right)}_{5}C\mathcal{l}\right]C{\mathcal{l}}_2+AgN{O}_3\stackrel{}{\to }AgC\mathcal{l}\downarrow \left(2mol\right)$  

x = 5

In H₂O (polar solvent) dibromophenol derivative and in CS₂ (non-polar solvent moneobromo phenol derivate is obtained.

3d => 4d => 5d CFSE increases for the same ligands.

Factual
⇒ leaching methods is used for those metal in which metal is more soluble than impurities and these are Al, Au, Ag, low grade Cu

σ bonded organometallic compound ⇒ M – C
σ-bond
and in π – bonded organo metallic compound
M – C
π bond
In ferrocene, there is π-bond