Explanation:

Fe(NH4)2(SO4)2(H2O)6 is a salt:

- The compound Fe(NH4)2(SO4)2(H2O)6 is a salt because it is formed by the reaction between a metal (Fe) and a non-metal (NH4 and SO4).
- Salts are formed when the positive ions (cations) of a metal combine with the negative ions (anions) of a non-metal.
- In this compound, Fe is the cation (iron) and NH4 and SO4 are the anions (ammonium and sulfate).
- The compound also contains water molecules (H2O), which are coordinated to the metal ion.
- The presence of water molecules in the compound indicates that it is a hydrated salt.

K4(Fe(CN)6) is a complex compound:

- The compound K4(Fe(CN)6) is a complex compound because it contains a central metal ion (Fe) surrounded by ligands (CN) that are bonded to it.
- Complex compounds are formed when a central metal ion forms coordinate bonds with ligands.
- In this compound, Fe is the central metal ion and CN is the ligand (cyanide).
- The ligands are bonded to the metal ion through coordinate bonds, where the ligand donates a pair of electrons to the metal ion.
- The compound also contains potassium ions (K+), which are not directly bonded to the central metal ion but are present to balance the charge of the complex.
- The coordination of the ligands to the central metal ion and the presence of potassium ions make it a complex compound.

Summary:

- Fe(NH4)2(SO4)2(H2O)6 is a salt because it is formed by the reaction between a metal (Fe) and a non-metal (NH4 and SO4), while K4(Fe(CN)6) is a complex compound because it contains a central metal ion (Fe) surrounded by ligands (CN) that are bonded to it.