Answer: Prussian blue (KFe[Fe(CN)6]) intensely blue precipitate.
- A Prussian blue (KFe[Fe(CN)6]) intensely blue precipitate
- B A pale yellow precipitate forming instead of any blue colour
- C A deep red colouration with no precipitate forming at all
- D No visible reaction occurring between the two reagents
Correct answer: A. Prussian blue (KFe[Fe(CN)6]) intensely blue precipitate
Explanation: Fe3+ (from FeCl3) + [Fe(CN)6]4- → KFe[Fe(CN)6] (Prussian blue), a mixed-valence Fe2+/Fe3+ complex with intense blue charge-transfer band.
The three common coordination geometries: octahedral (6 ligands), tetrahedral (4 ligands), and square planar (4 ligands in one plane).
Concept context
Study of compounds where a central metal atom is bonded to surrounding ligands. Covers nomenclature, types of isomerism, bonding theories (VBT, CFT), and applications in medicine, photography, and industry.