JEE Chemistry 2025 Question with Solution

Given: The listed reactions must be checked against known qualitative inorganic reactions and their observations.

Find: Which option set is correct.

From the solution text:

• The copper(II) salt with hexacyanoferrate does not give a blue precipitate; it gives a reddish-brown precipitate.
• The reaction $4FeCl_3 + 3K_4Fe(CN)_6$ is the known system that gives Prussian blue precipitate.
• The expression $37Cl_2 + 2KFe(CN)_6 \rightarrow 6KCl$ is chemically invalid.

Therefore:

1. Statement I is incorrect.
2. Statement II is incorrect.

The solution explicitly marks The Correct Option is C.

Therefore, the correct option is C.

The solution also notes a discrepancy: option (3) contains a product-side typographical error, but its reactant set is the chemically correct one for formation of Prussian blue.

Given: We must identify which listed reaction-observation pair is chemically valid.

Find: The correct choice among the four statements.

For the copper reaction, the solution states that $Cu^{2+}$ with hexacyanoferrate(II) forms a reddish-brown precipitate, not a blue precipitate. Hence the blue-precipitate claim in the copper-based statements is incorrect.

For the ferric chloride reaction, the solution identifies the well-known Prussian blue system:

This is the reaction associated with the blue precipitate. The source solution mentions that the product shown in the given question text is a typographical error, but the reactants are the correct set.

For the chlorine reaction, the solution states that

is chemically nonsensical and can be rejected.

Thus, the two statements being tested are both incorrect, and the keyed answer from the solution is C.

Therefore, the correct option is C.