$$Fe^{3+}$$ cation gives a prussian blue precipitate on addition of potassium ferrocyanide solution due to the formation of

We need to identify the compound responsible for the Prussian blue precipitate formed when $$Fe^{3+}$$ reacts with potassium ferrocyanide.

- $$Fe^{3+}$$ cation (from a ferric salt)

- Potassium ferrocyanide: $$K_4[Fe(CN)_6]$$, which provides the $$[Fe(CN)_6]^{4-}$$ ion

When $$Fe^{3+}$$ reacts with $$[Fe(CN)_6]^{4-}$$:

$$4Fe^{3+} + 3[Fe(CN)_6]^{4-} \rightarrow Fe_4[Fe(CN)_6]_3 \downarrow$$

- Charge from $$Fe^{3+}$$: $$4 \times (+3) = +12$$

- Charge from $$[Fe(CN)_6]^{4-}$$: $$3 \times (-4) = -12$$

- Net charge = 0 $$\checkmark$$

The compound $$Fe_4[Fe(CN)_6]_3$$ is known as Prussian blue (or ferric ferrocyanide). It is a deep blue insoluble precipitate and is a classic qualitative test for $$Fe^{3+}$$ ions.

Hence, the correct answer is Option D.